Low-cobalt and cobalt-free, high-energy cathode materials for lithium batteries

ABSTRACT

Described herein are low or no-cobalt materials useful as electrode active materials in a cathode for lithium or lithium-ion batteries. For example, compositions of matter are described herein, such as electrode active materials that can be incorporated into an electrode, such as a cathode. The disclosed electrode active materials exhibit high specific energy and voltage, and can also exhibit high rate capability and/or long operational lifetime.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/213,975, filed on Mar. 26, 2021, which claims the benefit of andpriority to U.S. Provisional Application No. 63/000,805, filed on Mar.27, 2020, which are hereby incorporated by reference in their entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with government support under Grant no.DE-EE0008845 and Grant no. DE-EE0007762 awarded by the Department ofEnergy. The government has certain rights in the invention.

FIELD

This invention is in the field of lithium batteries. This inventionrelates generally to cathodes containing low or no cobalt.

BACKGROUND

To date, all commercial high-energy-density lithium-ion battery cathodematerials contain cobalt, i.e., LiCoO₂ (LCO), Li[Ni_(a)Mn_(b)Co_(c)]O₂(a+b+c=1; NMC-abc), and Li[Ni_(1-x-y)Co_(x)Al_(y)]O₂ (NCA). The use ofcobalt in commercial lithium-ion battery cathodes involves a series ofchallenges. To begin with, cobalt is scarce and can only be found in afew places on Earth. Nearly two thirds of global cobalt mining comesfrom the Democratic Republic of Congo (DRC), a Central African countrywith unstable political regimes. In addition, cobalt mining in DRCsometimes skimps on environmental protections and exploits child labor.Even without disruptions of the global cobalt supply chain, demand forcobalt can outstrip production in the coming decade, with a projectedten-fold production increase of electric cars in 2025 compared to 2018.The price of cobalt has seen wild swings (for example $20,000-$95,000per metric ton in just one year). With rapid expansion of globalelectric mobility, there is a growing consensus to reduce cobalt usagein lithium-based battery cathode materials. Though cobalt-freecommercial cathodes exist, i.e., lithium iron phosphate and lithiummanganese oxide, they offer much lower energy content as compared tocobalt-containing cathodes and cannot meet the stringent requirements ofnext-generation automotive batteries for passenger electric vehicles.Emerging cobalt-free cathode technologies such as 5 V spinel oxides,layered lithium-excess oxides, sulfur, and metal fluorides allnecessitate a fundamental change of current lithium battery chemistry,which likely will take a decade or more development time.

Lithium transition-metal layered oxides are expected to continue to bethe cathode material of choice for portable electronics and passengerelectric cars at least through the next decade. However, thesematerials, despite varying formulations, universally contain cobalt.Cobalt is generally deemed essential for performance and stability.

SUMMARY

Described herein are low or no-cobalt materials useful as electrodeactive materials in a cathode for lithium or lithium ion batteries. Forexample, compositions of matter are described herein, such as electrodeactive materials. The electrode active materials can be incorporatedinto an electrode, such as a cathode. The electrode active material canbe in the form of a powder, which can be assembled as a cathode activematerial over a current collector, such as using slurry-based depositionor assembly techniques.

The disclosed electrode active materials can also be incorporated intoor used in an electrochemical cell. For example, the electrode activematerials can be incorporated into a cathode, and/or in anelectrochemical cell with an anode and an electrolyte positioned betweenthe cathode and the anode. Other components may also be used in anelectrochemical cell, such as a separator, current collectors,packaging, or the like. In some cases, one or multiple electrochemicalcells may be incorporated into or used in a battery. The cathode or theanode or both may independently comprise one or more of an activematerial, a current collector, a binder, or a conductive additive.

Example materials useful for the anode of an electrochemical cellincorporating the electrode active materials described herein as ananode active material include, but are not limited to, graphite, carbon,silicon, lithium titanate (Li₄Ti₅O₁₂), tin, antimony, zinc, phosphorous,lithium, or a combination thereof. In some examples, useful electrolytesinclude liquid electrolytes and solid electrolytes. Non-aqueouselectrolytes, such as ethylene carbonate or propylene carbonate, may beused.

An electrode active material may compriseLi_(a)Ni_(1-b-c)Co_(b)M_(c)O_(d), where a may be from 0.9 to 1.1, b maybe from 0 to 0.05, c may be from 0 to 0.67, d may be from 1.9 to 2.1,and M may be Mn, Al, Mg, Fe, Cr, B, Ti, Zr, Ga, Zn, V, Cu, Yb, Li, Na,K, F, Ba, Ca, Lu, Y, Nb, Mo, Ru, Rh, Ta, Pr, W, Ir, In, Tl, Sn, Sr, S,P, Cl, Ge, Sb, Er, Te, La, Ce, Nd, Dy, Eu, Sc, Se, Si, Tc, Pd, Pm, Sm,Gd, Tb, Ho, Tm, or any combination of these.

Advantageously, the electrode active materials described herein mayexhibit exceptional specific energy, which may indicate an amount ofenergy stored by the electrode active material per unit mass. Forexample, the electrode active materials exhibit or are characterized bya specific energy for a single discharge of from 600 Wh·kg⁻¹ to 1000Wh·kg⁻¹. In some examples, the specific energy for a single dischargemay be from 650 Wh·kg⁻¹ to 1000 Wh·kg⁻¹, from 700 Wh·kg⁻¹ to 1000Wh·kg⁻¹, from 750 Wh·kg⁻¹ to 1000 Wh·kg⁻¹, from 800 Wh·kg⁻¹ to 1000Wh·kg⁻¹, from 850 Wh·kg⁻¹ to 1000 Wh·kg⁻¹, from 900 Wh·kg⁻¹ to 1000Wh·kg⁻¹, or from 950 Wh·kg⁻¹ to 1000 Wh·kg⁻¹. The specific energy for asingle discharge cycle may correspond to a discharge within 5 V to 3 Vvs. Li⁺/Li, such as from 4.4 V to 3 V vs. Li⁺/Li. In some examples, thespecific energy for a single discharge may correspond to a dischargefrom 5 V to 3.1 V vs. Li⁺/Li. In some examples, the specific energy fora single discharge may correspond to a discharge from 5 V to 3.2 V vs.Li⁺/Li. In some examples, the specific energy for a single discharge maycorrespond to a discharge from 5 V to 3.3 V vs. Li⁺/Li. In someexamples, the specific energy for a single discharge may correspond to adischarge from 5 V to 3.4 V vs. Li⁺/Li. In some examples, the specificenergy for a single discharge may correspond to a discharge from 5 V to3.5 V vs. Li⁺/Li. In some examples, the specific energy for a singledischarge may correspond to a discharge from 4.9 V to 3 V vs. Li⁺/Li. Insome examples, the specific energy for a single discharge may correspondto a discharge from 4.8 V to 3 V vs. Li⁺/Li. In some examples, thespecific energy for a single discharge may correspond to a dischargefrom 4.7 V to 3 V vs. Li⁺/Li. In some examples, the specific energy fora single discharge may correspond to a discharge from 4.6 V to 3 V vs.Li⁺/Li. In some examples, the specific energy for a single discharge maycorrespond to a discharge from 4.5 V to 3 V vs. Li⁺/Li. In someexamples, the single discharge may correspond to a discharge at a rateof 1 C. In some examples, the single discharge may correspond to adischarge at a rate of C/10. In some examples, the single discharge maycorrespond to a discharge at a temperature of 25° C. In some examples,the single discharge may correspond to a discharge of an electrodecomprising an electrode active material content of at least 90% byweight and an electrode active material areal capacity loading of atleast 2.0 mAh·cm⁻². In some examples, the single discharge maycorrespond to a discharge in a coin-format half battery cell paired withlithium metal as the counter electrode in a commercial non-aqueouselectrolyte.

Advantageously, the electrode active materials described herein mayexhibit exceptionally high voltage during discharge, which arecharacterized by a dQ·dV⁻¹ curve exhibiting a minimum of exceptionallyhigh voltage during discharge. To determine dQ·dV⁻¹, lithium metal coincells can be cycled at a specific rate, such as at a C/10 rate, over avoltage range, such as from 2.8 V to 4.4 V vs. Li⁺/Li. The cycling dataused for calculating dQ/dV can be determined using even voltage steps,such as steps separated by 0.02 V steps, for example. The dQ/dV value ateach voltage can be calculated by the formula in Eq. 1. The charge, Q₂,in Eq. 1 is the total charge at the voltage of interest, V₂, with theproceeding data point at voltage V₁ and total charge for that charge ordischarge cycle at Q₁. When the data used for dQ/dV calculation isacquired at an even voltage step, such as every 0.02 V, ΔV may be thesame value, such as 0.02 V, with the unit mAh·g⁻¹V⁻¹. Use of voltagesteps of about 0.02 V between acquired data points can be useful forpreventing noise from impacting the magnitude of the mAh·g⁻¹V⁻¹, whichcan increase to very large values when ΔV is set to small values.

$\begin{matrix}{\frac{dQ}{dV} = {\frac{Q_{2} - Q_{1}}{V_{2} - V_{1}} = \frac{\Delta Q}{\Delta V}}} & {{Eq}.\mspace{14mu} 1}\end{matrix}$

Then data points (x, y) can be plotted with x=½(V₁+V₂) and

${y = \frac{Q_{2} - Q_{1}}{V_{2} - V_{1}}},$

and a minimum value (e.g., lowest negative peak or nadir) can bedetermined.

For example, the electrode active materials exhibit or are characterizedby a dQ·dV⁻¹ curve which has a minimum of −300 mAh·g⁻¹V⁻¹ or lower, suchas at a voltage of from 4.15 V to 4.30 V vs. Li⁺/Li, during a singledischarge. As used herein, a minimum may refer to a lowest magnitude,such as in a particular range, and may refer to a negative peak ornadir, representing a local minimum value, which may, in some cases, bean absolute minimum value. In some examples, the minimum may have amagnitude of from about −300 mAh·g⁻¹V⁻¹ to about −3000 mAh·g⁻¹V⁻¹. Insome examples, the dQ·dV⁻¹ curve has a minimum during a single dischargeat a voltage from 4.16 V to 4.30 V vs. Li⁺/Li, from 4.17 V to 4.30 V vs.Li⁺/Li, from 4.18 V to 4.30 V vs. Li⁺/Li, from 4.19 V to 4.30 V vs.Li⁺/Li, from 4.20 V to 4.30 V vs. Li⁺/Li, from 4.21 V to 4.30 V vs.Li⁺/Li, or from 4.22 V to 4.30 V vs. Li⁺/Li. In some examples, thedQ·dV⁻¹ curve has a minimum during a single discharge of at least −400mAh·g⁻¹V⁻¹, at least −500 mAh·g⁻¹V⁻¹, at least −600 mAh·g⁻¹V⁻¹, at least−700 mAh·g⁻¹V⁻¹, at least −800 mAh·g⁻¹V⁻¹, at least −900 mAh·g⁻¹V⁻¹, atleast −1000 mAh·g⁻¹V⁻¹, at least −1200 mAh·g⁻¹V⁻¹, at least −1400mAh·g⁻¹V⁻¹, at least −1600 mAh·g⁻¹V⁻¹, at least −1800 mAh·g⁻¹V⁻¹, or atleast −2000 mAh·g⁻¹V⁻¹. In some examples, the single discharge maycorrespond to a discharge at a rate of C/10. In some examples, thesingle discharge may correspond to a discharge at a temperature of 25°C. In some examples, the single discharge may correspond to a dischargeof an electrode comprising an electrode active material content of atleast 90% by weight and an electrode active material areal capacityloading of at least 2.0 mAh·cm⁻². In some examples, the single dischargemay correspond to a discharge in a coin-format half battery cell pairedwith lithium metal as the counter electrode infused with a commercialnon-aqueous electrolyte. In some examples, a cobalt-free electrodeactive material (LiNi_(1-c)M_(c)O_(d)), such as comprisingLiNi_(1-c1-c2)Mn_(c1)Al_(c2)O_(d) (NMA), may exhibit or be characterizedby a dQ·dV⁻¹ curve having a minimum at a voltage of 4.20 V vs. Li⁺/Li orabove, such as from 4.20 V to 4.30 V vs. Li⁺/Li, during a singledischarge at C/10 rate and 25° C. Here, c1 and c2 total to c and may befrom 0 to 0.67, for example.

Advantageously, a high specific energy of the disclosed electrode activematerials may be retained after a large number of charge-dischargecycles. In some cases, the specific energy may decrease as a function ofthe number of charge-discharge cycles. For example, the electrode activematerial may exhibit or be characterized by an original specific energyfor a first discharge and a specific energy for another discharge afterabout 500 charge-discharge cycles that is at least 80% of the originalspecific energy of from 600 Wh·kg⁻¹ to 1000 Wh·kg⁻¹. Optionally, thespecific energy for a discharge after about 1000 charge-discharge cyclesmay be at least 80% of the original specific energy of from 600 Wh·kg⁻¹to 1000 Wh·kg⁻¹. Optionally, the specific energy for a discharge afterabout 500 charge-discharge cycles may be at least 85% of the originalspecific energy, at least 90% of the original specific energy, or atleast 95% of the original specific energy of from 600 Wh·kg⁻¹ to 1000Wh·kg⁻¹. Optionally, the specific energy for a discharge after about 100charge-discharge cycles may be at least 95% of the original specificenergy of from 600 Wh·kg⁻¹ to 1000 Wh·kg⁻¹. In a specific example, theelectrode active material may exhibit or be characterized by an originalspecific energy for a first discharge from 600 Wh·kg⁻¹ to 1000 Wh·kg⁻¹and a specific energy for another discharge after about 500charge-discharge cycles from 480 Wh·kg⁻¹ to 1000 Wh·kg⁻¹. In oneexample, the electrode active material may exhibit or be characterizedby an original specific energy for a first discharge from 600 Wh·kg⁻¹ to1000 Wh·kg⁻¹ and a specific energy for another discharge after 1000charge-discharge cycles from 480 Wh·kg⁻¹ to 1000 Wh·kg⁻¹. In anotherexample, the electrode active material may exhibit or be characterizedby an original specific energy for a first discharge cycle from 600Wh·kg⁻¹ to 1000 Wh·kg⁻¹ and a specific energy for another dischargebetween after 500 charge-discharge cycles from 540 Wh·kg⁻¹ to 1000Wh·kg⁻¹. In another example, the electrode active material may exhibitor be characterized by an original specific energy for a first dischargecycle from 600 Wh·kg⁻¹ to 1000 Wh·kg⁻¹ and a specific energy for anotherdischarge between after 100 charge-discharge cycles from 570 Wh·kg⁻¹ to1000 Wh·kg⁻¹. These discharges for measuring a specific energy may befrom 5 V to 3 V vs. Li⁺/Li, or from 5 V to a voltage greater than 3 Vvs. Li⁺/Li, such as 3.1 V, 3.2 V, 3.3 V, 3.4 V, or 3.5 V vs. Li⁺/Li, orfrom a voltage lower than 5 V, such as 4.9 V, 4.8 V, 4.7 V, 4.6 V, or4.5 V, to 3 V vs. Li⁺/Li. In some examples, the discharge may correspondto a discharge of an electrode comprising an electrode active materialcontent of at least 90% by weight and an electrode active material arealcapacity loading of at least 2.0 mAh·cm⁻². In some examples, thedischarge may correspond to a discharge in a pouch-format full batterycell paired with graphite as the counter electrode, infused with acommercial non-aqueous electrolyte.

An electrode active material may compriseLi_(a)Ni_(1-b-c)Co_(b)M_(c)O_(d), where a may be from 0.9 to 1.1, b maybe from 0 to 0.1, c may be from 0 to 0.67, d may be from 1.9 to 2.1, andM may be Mn, Al, Mg, Fe, Cr, B, Ti, Zr, Ga, Zn, V, Cu, Yb, Li, Na, K, F,Ba, Ca, Lu, Y, Nb, Mo, Ru, Rh, Ta, Pr, W, Ir, In, Tl, Sn, Sr, S, P, Cl,Ge, Sb, Er, Te, La, Ce, Nd, Dy, Eu, Sc, Se, Si, Tc, Pd, Pm, Sm, Gd, Tb,Ho, Tm, or any combination of these; and where the electrode activematerial may exhibit or be characterized by a specific energy for a 1 Cdischarge between 5 V and 3 V vs. Li⁺/Li at 25° C. that is from 80% to100% of a specific energy for a C/10 discharge between 5 V and 3 V vs.Li⁺/Li at 25° C. As used herein, the recitation of a discharge between arange of two voltages can optionally include a discharge between a rangeof two intermediate voltages. For example, a discharge between 5 V and 3V vs. Li⁺/Li can include a discharge from 5 V to 3 V vs. Li⁺/Li, from 4V to 3 V vs. Li⁺/Li, from 5 V to 4 V vs. Li⁺/Li, from 4.5 V to 3 V vs.Li⁺/Li, etc. In some examples, the specific energy for the 1 C dischargebetween 5 V and 3 V vs. Li⁺/Li at 25° C. may be from 85% to 100% of thespecific energy for a C/10 discharge between 5 V and 3 V vs. Li⁺/Li at25° C. In some examples, the specific energy for the 1 C dischargebetween 5 V and 3 V vs. Li⁺/Li at 25° C. may be from 90% to 100% of thespecific energy for a C/10 discharge between 5 V and 3 V vs. Li⁺/Li at25° C. In some examples, the specific energy for the 1 C dischargebetween 5 V and 3 V vs. Li⁺/Li at 25° C. may be from 600 Wh·kg⁻¹ to 1000Wh·kg⁻¹. In some examples, the specific energy for the 1 C dischargebetween 5 V and 3 V vs. Li⁺/Li at 25° C. may be from 750 Wh·kg⁻¹ to 1000Wh·kg⁻¹. In some examples, the discharge may correspond to a dischargeof an electrode comprising an electrode active material content of atleast 90% by weight and an electrode active material areal capacityloading of at least 2.0 mAh·cm⁻². In some examples, the discharge maycorrespond to a discharge in a coin-format half battery cell paired withlithium metal as the counter electrode infused with a commercialnon-aqueous electrolyte.

For the electrode active materials described herein, M can optionally beone or a subset of the metals and non-metals identified above. Forexample, M may be a combination of Mn and Al. M may be a combination ofMn, Mg, and Al. M may be a combination of Mn and Mg. M may be acombination of Al and Mg. M may be a combination of Ti, Mg, and Al. Mmay be or comprise Fe. M may be or comprise Zn. M may be or compriseboth Fe and Zn. The disclosed electrode active materials may be free orsubstantially free of Co. For example, b may be 0 or b may be less than0.01. The disclosed electrode active materials may have Li present in anexcess or may be Li deficient. Optionally, a may be from 0.9 to 1.Optionally, a may be from 1 to 1.1. In some cases b may be from 0 to0.01 and c may be from 0 to 0.1. Optionally, c may be from 0.1 to 0.5,from 0.1 to 0.2, or from 0.2 to 0.4. Optionally, d may be from 1.95 to2.05.

The electrode active materials may have various different physical orother properties, which may be different from those of otherconventional materials. In some examples, the electrode active materialmay exhibit or be characterized by a tapped density of from 2.0 g·cm⁻³to 3.5 g·cm⁻³. In some examples, the electrode active material mayexhibit or be characterized by a tapped density of from 2.3 g·cm⁻³ to3.0 g·cm⁻³. The crystal structure of the electrode active materials mayalso be distinct from other conventional materials. For example, in somecases, only a portion of the electrode active material may comprise orbe characterized by a rhombohedral crystal structure or a rhombohedralR3m crystal structure. In some cases, the rhombohedral crystal structureor the rhombohedral R3m crystal structure may be or comprise a majority(e.g., 50% or more by volume) of the electrode active material. Therhombohedral crystal structure or a rhombohedral R3m crystal structuremay be 50% or more by volume, 55% or more by volume, 60% or more byvolume, 65% or more by volume, 70% or more by volume, 75% or more byvolume, 80% or more by volume, 85% or more by volume, 90% or more byvolume, 95% or more by volume, or 99% or more by volume.

The electrode active material may be in the form of particles, which mayhave differences between the surface of the particles and an interior orbulk of the particles. In some examples, the particles may havecross-sectional dimensions of from 500 nm to 30 μm. Optionally, theelectrode active material may have or be characterized by a surfaceregion and a bulk region, such as where the surface region correspondsto a first portion of the active material or particles thereof within20% of a cross-sectional dimension from a surface of the active materialor particles thereof, and where the bulk region corresponds to a secondportion of the active material or particles thereof deeper than thesurface region. As examples of characteristics of the bulk region, thebulk region may be free or substantially free of or otherwise notexhibit a spinel (for example, P4₃32 and Fd3m) crystal structure, alithium-excess (for example, C2/m) crystal structure or a rock-salt (forexample, Fm3m) crystal structure. In some cases, at least a portion ofthe surface region may comprise or be characterized by a spinel (forexample, P4₃32 and Fd3m) crystal structure, a lithium-excess (forexample, C2/m) crystal structure, a rock-salt (for example, Fm3m)crystal structure, or a combination thereof. In another example, thebulk region may be free or substantially free of or otherwise notexhibit a polyanionic structure, such as LiFePO₄ (Pmnb/Pnma). In anotherexample, at least a portion of the surface region may comprise or becharacterized by a polyanionic structure, such as LiFePO₄ (Pmnb/Pnma).

Control over the morphology of particles comprising the electrode activematerial may be useful for achieving desirable properties, such as thetapped densities disclosed herein, the specific energies disclosedherein, the rate capabilities disclosed herein, and/or the operationallifetimes disclosed herein. Advantageously, the particles of theelectrode active material may comprise secondary particles. For example,the secondary particles may each comprise a plurality of primaryparticles of smaller size. For example, each secondary particle maycomprise from 1 to 100,000,000 or more primary particles. The secondaryparticles may have cross-sectional dimensions of from 500 nm to 30 μm,such as from 500 nm to 2.5 μm, from 2.5 μm to 7.5 μm, from 7.5 μm to 15μm, or from 15 μm to 30 μm. Optionally, the secondary particles aresubstantially monodisperse, such as where a cross-sectional distributionof the plurality of the secondary particles exhibits a single sizedistribution. In some examples the secondary particles are polydisperse,such as where a first portion of the secondary particles have a firstcross-sectional dimension distribution and a second portion have asecond cross-sectional dimension distribution that is at least a factorof 10 larger than the first cross-sectional dimension distribution. Insome examples, the plurality of secondary particles are substantiallyspherical in shape. The primary particles, which may make up thesecondary particles, may have cross-sectional dimensions of from 10 nmto 10 μm, such as from 10 nm to 100 nm, from 100 nm to 1000 nm, or from1 μm to 10 μm. The primary particles may be substantially monodisperseor exhibit a monodisperse size distribution. In some cases, a secondaryparticle may comprise a single primary particle, and may be referred toas single-crystalline or single-crystal.

As described above, the electrode active material may exhibit a longoperational lifetime. For example, the electrode active material mayexhibit or be characterized by a specific energy after 500charge-discharge cycles of more than 80% of an original specific energyof from 600 Wh·kg⁻¹ to 1000 Wh·kg⁻¹. Optionally, the electrode activematerial may exhibit or be characterized by a specific energy after 1000charge-discharge cycles of more than 80% of an original specific energyof from 600 Wh·kg⁻¹ to 1000 Wh·kg⁻¹. Optionally, the electrode activematerial may exhibit or be characterized by a specific energy after 500charge-discharge cycles of more than 90% of an original specific energyof from 600 Wh·kg⁻¹ to 1000 Wh·kg⁻¹. Optionally, the electrode activematerial may exhibit or be characterized by a specific energy after 100charge-discharge cycles of more than 95% of an original specific energyof from 600 Wh·kg⁻¹ to 1000 Wh·kg⁻¹.

Without wishing to be bound by any particular theory, there can bediscussion herein of beliefs or understandings of underlying principlesrelating to the invention. It is recognized that regardless of theultimate correctness of any mechanistic explanation or hypothesis, anembodiment of the invention can nonetheless be operative and useful.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 provides a schematic illustration of an example electrodecomprising an electrode active material and a current collectoraccording to at least some aspects of the present disclosure.

FIG. 2 provides a schematic illustration of an example electrochemicalcell according to at least some aspects of the present disclosure.

FIG. 3 provides X-ray diffraction (XRD) patterns ofLiNi_(0.9)Co_(0.05)Mn_(0.05)O₂, LiNi_(0.9)Co_(0.05)Al_(0.05)O₂,LiNi_(0.9)Mn_(0.05)Al_(0.05)O₂,LiNi_(0.9)Co_(0.04)Mn_(0.04)Al_(0.01)Mg_(0.01)O₂, andLiNi_(0.9)Mn_(0.05)Mg_(0.05)O₂.

FIG. 4 provides scanning electron microscopy (SEM) images ofLiNi_(0.9)Co_(0.05)Mn_(0.05)O₂.

FIG. 5 provides scanning electron microscopy (SEM) images ofLiNi_(0.9)Co_(0.05)Al_(0.05)O₂.

FIG. 6 provides scanning electron microscopy (SEM) images ofLiNi_(0.9)Co_(0.04)Mn_(0.04)Al_(0.01)Mg_(0.01)O₂.

FIG. 7 provides galvanostatic charge-discharge voltage profiles ofLiNi_(0.9)Co_(0.05)Mn_(0.05)O₂, LiNi_(0.9)Co_(0.05)Al_(0.05)O₂ andLiNi_(0.9)Co_(0.04)Mn_(0.04)Al_(0.01)Mg_(0.01)O₂ in lithium-ion cellspaired with lithium metal.

FIG. 8 provides discharge voltage profiles (upper) and evolution ofspecific energy as a function of cycle number (lower) ofLiNi_(0.9)Co_(0.05)Mn_(0.05)O₂, LiNi_(0.9)Co_(0.05)Al_(0.05)O₂ andLiNi_(0.9)Co_(0.04)Mn_(0.04)Al_(0.01)Mg_(0.01)O₂ in lithium-ion cellspaired with graphite.

FIG. 9 provides scanning electron microscopy (SEM) images ofLiNi_(0.9)Mn_(0.05)Al_(0.05)O₂.

FIG. 10 provides galvanostatic charge-discharge voltage profiles ofLiNi_(0.9)Mn_(0.05)Al_(0.05)O₂ and LiNi_(0.9)Mn_(0.05)Mg_(0.05)O₂ inlithium-ion cells paired with lithium metal.

FIG. 11 provides discharge voltage profiles (upper) and evolution ofspecific energy as a function of cycle number (lower) ofLiNi_(0.9)Mn_(0.05)Al_(0.05)O₂ and LiNi_(0.9)Mn_(0.05)Mg_(0.05)O₂ inlithium-ion cells paired with graphite.

FIG. 12 provides dQ·dV⁻¹ curves of LiNi_(0.90)Co_(0.05)Mn_(0.05)O₂(blue), LiNi_(0.90)Co_(0.05)Al_(0.05)O₂ (red),LiNi_(0.90)Co_(0.04)Mn_(0.04)Al_(0.01)Mg_(0.01)O₂ (green), andLiNi_(0.90)Mn_(0.05)Al_(0.05)O₂ (gray) in coin half battery cells (vs.Li metal) at 25° C. during C/10 formation cycles.

FIG. 13 provides dQ·dV⁻¹ curves of LiNi_(0.90)Co_(0.05)Mn_(0.05)O₂,LiNi_(0.90)Co_(0.05)Al_(0.05)O₂,LiNi_(0.90)Co_(0.04)Mn_(0.04)Al_(0.01)Mg_(0.01)O₂, andLiNi_(0.90)Mn_(0.05)Al_(0.05)O₂ in coin half battery cells (vs. Limetal) at 25° C. during C/3 cycles.

FIG. 14 provides Rietveld refinement of the X-ray diffraction (XRD)patterns of pristine LiNi_(0.90)Co_(0.05)Mn_(0.05)O₂ (NCM),LiNi_(0.90)Co_(0.05)Al_(0.05)O₂ (NCA),LiNi_(0.90)Co_(0.04)Mn_(0.04)Al_(0.01)Mg_(0.01)O₂ (NCMAM), andLiNi_(0.90)Mn_(0.05)Al_(0.05)O₂ (NMA).

FIG. 15 provides cross-sectional scanning electron microscopy(SEM)/energy-dispersive X-ray spectroscopy (EDX) images ofLiNi_(0.90)Co_(0.05)Mn_(0.05)O₂ (NCM), LiNi_(0.90)Co_(0.05)Al_(0.05)O₂(NCA), LiNi_(0.90)Co_(0.04)Mn_(0.04)Al_(0.01)Mg_(0.01)O₂ (NCMAM), andLiNi_(0.90)Mn_(0.05)Al_(0.05)O₂ (NMA), showing elemental distribution ofthe four cathode materials after calcination.

FIG. 16 provides data showing a rate capability comparison ofLiNi_(0.90)Co_(0.05)Mn_(0.05)O₂ (NCM), LiNi_(0.90)Co_(0.05)Al_(0.05)O₂(NCA), LiNi_(0.90)Co_(0.04)Mn_(0.04)Al_(0.01)Mg_(0.01)O₂ (NCMAM), andLiNi_(0.90)Mn_(0.05)Al_(0.05)O₂ (NMA) in coin half battery cells (vs. Limetal) at 25° C. up to a 5 C discharge rate at a constant C/10 chargerate, normalized to their respective specific capacity at C/10 rate.

FIG. 17 provides discharge curves of LiNi_(0.90)Co_(0.05)Mn_(0.05)O₂,LiNi_(0.90)Co_(0.05)Al_(0.05)O₂,LiNi_(0.90)Co_(0.04)Mn_(0.04)Al_(0.01)Mg_(0.01)O₂, andLiNi_(0.90)Mn_(0.05)Al_(0.05)O₂ in coin half battery cells (vs. Limetal) at 25° C. up to a 5 C discharge rate at a constant C/10 chargerate.

FIG. 18 provides data showing long-term cycling ofLiNi_(0.90)Co_(0.05)Mn_(0.05)O₂ (NCM), LiNi_(0.90)Co_(0.05)Al_(0.05)O₂(NCA), LiNi_(0.90)Co_(0.04)Mn_(0.04)Al_(0.01)Mg_(0.01)O₂ (NCMAM), andLiNi_(0.90)Mn_(0.05)Al_(0.05)O₂ (NMA) in pouch full battery cells (vs.graphite) at 25° C. over 1000 cycles at a C/2-1 C charge-discharge rate.

FIG. 19 provides differential scanning calorimetry (DSC) profiles ofLiNi_(0.90)Co_(0.05)Mn_(0.05)O₂, LiNi_(0.90)Co_(0.05)Al_(0.05)O₂,LiNi_(0.90)Co_(0.04)Mn_(0.04)Al_(0.01)Mg_(0.01)O₂, andLiNi_(0.90)Mn_(0.05)Al_(0.05)O₂ charged to 220 mAh·g⁻¹ mixed with 1.0 MLiPF₆/EC-EMC (3:7)+2% VC at a weight ratio of ˜6:4.

FIG. 20 provides scanning electron microscopy (SEM) images of LiNiO₂.

FIG. 21 provides galvanostatic charge-discharge voltage profiles ofLiNiO₂ and LiNi_(0.9)Mn_(0.05)Al_(0.05)O₂ in lithium-ion cells pairedwith lithium metal.

FIG. 22 provides dQ·dV⁻¹ curves of LiNiO₂ in coin half battery cells(vs. Li metal) at 25° C. during C/10 formation cycles.

FIG. 23 provides dQ·dV⁻¹ curves of LiNi_(0.98)Ta_(0.02)O₂ in coin halfbattery cells (vs. Li metal) at 25° C. during C/10 formation cycles.

FIG. 24 provides dQ·dV⁻¹ curves of LiNi_(0.98)Zr_(0.02)O₂ in coin halfbattery cells (vs. Li metal) at 25° C. during C/10 formation cycles.

FIG. 25 provides dQ·dV⁻¹ curves of LiNi_(0.98)Mg_(0.02)O₂ in coin halfbattery cells (vs. Li metal) at 25° C. during C/10 formation cycles.

FIG. 26 provides galvanostatic charge-discharge voltage profiles (upper)and evolution of specific capacity as a function of cycle number (lower)of LiNi_(0.9)Mn_(0.05)Al_(0.05)O₂ with varying calcination conditions inlithium-ion cells paired with lithium metal.

FIG. 27 provides dQ·dV⁻¹ curves of LiNi_(0.90)Mn_(0.05)Al_(0.05)O₂synthesized by two calcination conditions in coin half battery cells(vs. Li metal) at 25° C. during C/10 formation cycles.

FIG. 28 provides scanning electron microscopy (SEM) images ofNi_(0.9)Co_(0.05)Mn_(0.05)(OH)₂ or Ni_(0.9)Co_(0.05)Mn_(0.05)CO₃ withvarying co-precipitation conditions.

FIG. 29 provides cycling data of co-precipitated LiNi_(0.95)Mn_(0.05)O₂and LiNi_(0.9)Mn_(0.05)Al_(0.05)O₂ (Al-bearing LiNi_(0.95)Mn_(0.05)O₂; 5mol %) via calcination, evaluated in coin half battery cells paired withLi metal at a C/3 rate and 25° C.

DETAILED DESCRIPTION

This disclosure provides a novel class of low-cobalt or cobalt-freelithium transition-metal layered oxides, useful as positive electrode(cathode) active materials for rechargeable lithium-based batteries. Thedescribed active materials include those excluding cobalt, currentlyuniversally present in layered oxide cathodes in commercial lithium-ionbatteries. Instead, the described class of cathodes uses raw materialsof higher earth abundance and lower cost, more secure supply chains, andless adverse impacts on the environment.

The described active materials can be easily tuned in chemicalcompositions to provide high specific energy, high voltage, high ratecapability, and/or long operational lifetime over a wide temperaturerange (from subzero to elevated temperatures), as well as desirablesafety features under abuse (e.g., short circuit, overcharge, rupture).These active materials are readily compatible with existing componentsin commercial lithium-ion batteries, such as graphite/silicon anodes,polymeric separators, and nonaqueous aprotic carbonate-basedelectrolytes.

Cathodes of the described active materials have been evaluated andvalidated in pouch-format full battery cells. The active materials canbe synthesized via established industrial manufacturing processes, i.e.,metal co-precipitation, lithiation calcination, and optionallysubsequent surface treatments. A series of metals and/or non-metals areincorporated to enable desirable specific energy and rate capability,operational lifetime, and safety in the absence of cobalt or in very lowconcentrations of cobalt. The described cathodes demonstrate promise forfuture low-cobalt or cobalt-free, high-energy-density lithium-basedbatteries, including both lithium-ion and lithium-metal chemistries ineither liquid, semi-solid, or all-solid-state electrolyte systems.

With rapid expansion of global electric mobility, there is a growingconsensus to reduce cobalt usage in lithium-based battery cathodematerials. Though cobalt-free commercial cathodes exist (e.g., lithiumiron phosphate and lithium manganese oxide), they offer much lowerenergy contents and cannot meet the stringent requirements ofnext-generation automotive batteries for passenger electric vehicles.Emerging cobalt-free cathode technologies such as 5 V spinel oxides,layered lithium-excess oxides, sulfur, and metal fluorides allnecessitate a fundamental change of current lithium battery chemistry,which likely will take a decade or more development time.

Lithium transition-metal layered oxides have been and are expected tocontinue to be the cathode material of choice for portable electronicsand passenger electric cars at least through the next decade. However,these materials, despite varying formulations, universally containcobalt in significant amounts. Cobalt is deemed essential forperformance and stability, but is a scarce metal with a vulnerablesupply chain and has a high cost as a result. Plus, owing to hightoxicity and questionable mining practices in Central Africa, cobaltcauses unfavorable impacts on the environment. Different from allcommercial layered oxide cathodes, this disclosure relates to a newclass of cathode materials of high energy content with low or zerocobalt usage.

The use of cobalt in commercial lithium-ion battery cathodes involves aseries of challenges. To begin with, cobalt is scarce and can only befound in a few places on earth. Nearly two thirds of global cobaltmining comes from the Democratic Republic of Congo (DRC), a CentralAfrican country with unstable political regimes. In addition, cobaltmining in DRC sometimes skimps on environmental protections and exploitschild labor. Even without disruptions of the global cobalt supply chain,demand for cobalt can outstrip production in the coming decade, with aprojected ten-fold production increase of electric cars in 2025 comparedto 2018. In comparison, nickel, manganese, aluminum, iron, zinc, andmany other metals and non-metals, are far more earth-abundant andavailable. These metals and non-metals are also much less geographicallyconcentrated than cobalt.

The active materials described herein reduce the dependence on cobalt ofcommercial layered oxide cathodes for lithium-based batteries, thusleading to more secure supply chains, lower cost, and less adverseenvironmental impacts. In addition, through a tuning in chemicalcomposition and synthesis, the described cathode materials can offerhigh specific energy, high voltage, high rate capability, and/or longoperational lifetime over a wide temperature range, as well as desirablesafety features under abuse conditions, in comparison to commerciallayered oxide cathode materials.

Since cobalt suppresses nickel and lithium anti-site defects (i.e.,cation disorder) in layered oxides, cobalt elimination can adverselyaffect specific capacity, voltage, rate capability, and operationallifetime of the cathode material. Advantageously, the active materialsdescribed herein mitigate these issues by incorporating a series ofalternative metals and/or non-metals, besides nickel, which compensatefor the lack of cobalt. Advantageously, these alternative metals andnon-metals can be incorporated easily through co-precipitation,lithiation calcination, and/or subsequent surface treatments.Advantageously, the synthesis comprising co-precipitation, lithiationcalcination, and/or subsequent surface treatments is useful, or in somecases critical, to mitigate the issues of specific capacity, voltage,rate capability, and operational lifetime of the cathode materialwithout cobalt.

Besides portable electronics and electric vehicles, the describedcathode active materials can be useful in unmanned aerial systems,robots, military batteries, and large-scale energy storage systems. Theflexibility in compositional designs can enable cathode materials witheither very high specific energy and rate capability or very longoperational lifetime, geared towards a variety of market needs.

Electrode Active Materials

The electrode active materials described herein include those exhibitinghigh specific energy measured on a cathode level, such as from about 600Wh·kg⁻¹ to about 1000 Wh·kg⁻¹. Example specific energies may be from 625Wh·kg⁻¹ to 1000 Wh·kg⁻¹, from 650 Wh·kg⁻¹ to 1000 Wh·kg⁻¹, from 675Wh·kg⁻¹ to 1000 Wh·kg⁻¹, from 700 Wh·kg⁻¹ to 1000 Wh·kg⁻¹, from 725Wh·kg⁻¹ to 1000 Wh·kg⁻¹, from 750 Wh·kg⁻¹ to 1000 Wh·kg⁻¹, from 775Wh·kg⁻¹ to 1000 Wh·kg⁻¹, from 800 Wh·kg⁻¹ to 1000 Wh·kg⁻¹, from 825Wh·kg⁻¹ to 1000 Wh·kg⁻¹, from 850 Wh·kg⁻¹ to 1000 Wh·kg⁻¹, from 875Wh·kg⁻¹ to 1000 Wh·kg⁻¹, from 900 Wh·kg⁻¹ to 1000 Wh·kg⁻¹, from 925Wh·kg⁻¹ to 1000 Wh·kg⁻¹, from 950 Wh·kg⁻¹ to 1000 Wh·kg⁻¹, or from 975Wh·kg⁻¹ to 1000 Wh·kg⁻¹. The specific energy can correspond to adischarge from about 5 V to about 3 V vs. Li⁺/Li, for example. It willbe appreciated that some electrode active materials can discharge tolower voltages, such as about 2 V vs. Li⁺/Li, which can allow someelectrode active materials to exhibit specific energies significantlyhigher than if they are only discharged to about 3 V vs. Li⁺/Li orgreater. Additionally, some electrode active materials can be charged tovoltages higher than about 5 V vs. Li⁺/Li, providing some additionalenergy. For comparison purposes, discharging from a voltage higher thanabout 5 V vs. Li⁺/Li or to a voltage lower than about 3 V vs Li⁺/Li maynot provide the same information as a discharge from about 5 V to about3 V vs Li⁺/Li. The specific energy can correspond to a discharge at aparticular temperature, such as room temperature, 25° C. It will beappreciated that some electrode active materials may exhibit differentspecific energies and rate capabilities at different temperatures. Thespecific energy can correspond to a discharge at a particular dischargerate, such as 1 C or C/10. It will be appreciated that some electrodeactive materials may exhibit different specific energies when dischargedat different rates. The specific energy can correspond to a discharge ofan electrode of a particular composition and thickness, such as thosecomprising an electrode active material content of at least 90% byweight and an electrode active material areal capacity loading of atleast 2.0 mAh·cm⁻². It will be appreciated that some electrode activematerials may exhibit different specific energies in electrodes ofdifferent compositions or thicknesses. The specific energy cancorrespond to a discharge of an electrode in a particular battery cellconfiguration, such as a coin-format half battery cell paired withlithium metal as the counter electrode infused with a commercialnon-aqueous electrolyte. It will be appreciated that some electrodeactive materials may exhibit different specific energies in differentbattery cell configurations.

The electrode active materials described herein include those exhibitinga high voltage measured on a cathode level, such as from 4.15 V to 4.30V vs. Li⁺/Li, at a minimum of from −300 mAh·g⁻¹V⁻¹ to −3000 mAh·g⁻¹V⁻¹,in a dQ·dV⁻¹ curve during discharge. Example high voltages may be from4.16 V to 4.30 V vs. Li⁺/Li, from 4.17 V to 4.30 V vs. Li⁺/Li, from 4.18V to 4.30 V vs. Li⁺/Li, from 4.19 V to 4.30 V vs. Li⁺/Li, from 4.20 V to4.30 V vs. Li⁺/Li, from 4.21 V to 4.30 V vs. Li⁺/Li, or from 4.22 V to4.30 V vs. Li⁺/Li. In some examples, the minimum in a dQ·dV⁻¹ curveduring discharge may be −400 mAh·g⁻¹V⁻¹ or lower, may be −500 mAh·g⁻¹V⁻¹or lower, −600 mAh·g⁻¹V⁻¹ or lower, −700 mAh·g⁻¹V⁻¹ or lower, −800mAh·g⁻¹V⁻¹ or lower, −900 mAh·g⁻¹V⁻¹ or lower, −1000 mAh·g⁻¹V⁻¹ orlower, −1200 mAh·g⁻¹V⁻¹ or lower, −1400 mAh·g⁻¹V⁻¹ or lower, −1600mAh·g⁻¹V⁻¹ or lower, −1800 mAh·g⁻¹V⁻¹ or lower, or −2000 mAh·g⁻¹V⁻¹ orlower. It will be appreciated that a dQ·dV⁻¹ curve may exhibit maximumsduring charge at voltages significantly higher than those of minimumsduring discharge. A maximum may refer to a highest magnitude, such as ina particular range, and may refer to a positive peak or zenith,representing a local maximum value, which may, in some cases, be anabsolute maximum value. For comparison purposes, voltages of maximumsduring charge in a dQ·dV⁻¹ curve may not provide the same information asthose of minimums during discharge in said dQ·dV⁻¹ curve. The voltagecan correspond to a method for calculation of the dQ·dV⁻¹ curves, suchas a voltage sampling step of 0.02 V. It will be appreciated that somecalculation methods may exhibit different voltages and/or minimums ofdifferent values expressed by mAh·g⁻¹V⁻¹ in dQ·dV⁻¹ curves duringdischarge. The voltage can correspond to a discharge at a particulartemperature, such as room temperature, 25° C. It will be appreciatedthat some electrode active materials may exhibit different voltages atdifferent temperatures. The voltage can correspond to a discharge at aparticular discharge rate, such as C/10. It will be appreciated thatsome electrode active materials may exhibit different voltages whendischarged at different rates. The voltage can correspond to a dischargeof an electrode of a particular composition and thickness, such as thosecomprising an electrode active material content of at least 90% byweight and an electrode active material areal capacity loading of atleast 2.0 mAh·cm⁻². It will be appreciated that some electrode activematerials may exhibit different voltages in electrodes of differentcompositions or thicknesses. The voltage can correspond to a dischargeof an electrode in a particular battery cell configuration, such as acoin-format half battery cell paired with lithium metal as the counterelectrode infused with a commercial non-aqueous electrolyte. It will beappreciated that some electrode active materials may exhibit differentvoltages in different battery cell configurations

A wide variety of compositions for the electrode active materials arecontemplated herein. In general, the electrode active materials compriseor are characterized by a chemical formula ofLi_(a)Ni_(1-b-c)Co_(b)M_(c)O_(d). Here, M represents one or more metalsand/or non-metals, such as Mn, Al, Mg, Fe, Cr, B, Ti, Zr, Ga, Zn, V, Cu,Yb, Li, Na, K, F, Ba, Ca, Lu, Y, Nb, Mo, Ru, Rh, Ta, Pr, W, Ir, In, Tl,Sn, Sr, S, P, Cl, Ge, Sb, Er, Te, La, Ce, Nd, Dy, Eu, Sc, Se, Si, Tc,Pd, Pm, Sm, Gd, Tb, Ho, Tm, or any combination of these.

The subscript a in the chemical formula Li_(a)Ni_(1-b-c)Co_(b)M_(c)O_(d)represents the relative amount of Li (lithium) in the electrode activematerials. In general, the amount of Li can vary from Li-rich toLi-deficient. For example, a may be from about 0.9 to about 1.1 ingeneral, or from 0.9 to 1.0 or from 1.0 to 1.1. In some cases, a may beor may be about 0.9, 0.905, 0.91, 0.915, 0.92, 0.925, 0.93, 0.935, 0.94,0.945, 0.95, 0.955, 0.96, 0.965, 0.97, 0.975, 0.98, 0.985, 0.99, 0.995,1, 1.005, 1.01, 1.015, 1.02, 1.025, 1.03, 1.035, 1.04, 1.045, 1.05,1.055, 1.06, 1.065, 1.07, 1.075, 1.08, 1.085, 1.09, 1.095, or 1.1.

The subscript b in the chemical formula Li_(a)Ni_(1-b-c)Co_(b)M_(c)O_(d)represents the relative amount of Co (cobalt) in the electrode activematerials. In general, the amount of Co is very low—such as where b isfrom 0 to 0.1 or from 0 to 0.05. In some cases, b may be or may be about0, 0.005, 0.010, 0.015, 0.020, 0.025, 0.030, 0.035, 0.040, 0.045, 0.050,0.055, 0.060, 0.065, 0.070, 0.075, 0.080, 0.085, 0.090, 0.095, or 0.100.

The subscript c in the chemical formula Li_(a)Ni_(1-b-c)Co_(b)M_(c)O_(d)represents the relative amount of metal(s) and/or non-metal(s) M in theelectrode active materials. In general, c can vary from about 0 to about0.67. In some cases, c may be from about 0 to about 0.5. Since M cancorrespond to one or multiple metals and/or non-metals, it will beappreciated that the stoichiometric coefficient for the individualmetals and/or non-metals may total to c. Example values for c may be ormay be about 0, 0.005, 0.010, 0.015, 0.020, 0.025, 0.030, 0.035, 0.040,0.045, 0.050, 0.055, 0.060, 0.065, 0.070, 0.075, 0.080, 0.085, 0.090,0.095, 0.100, 0.105, 0.110, 0.115, 0.120, 0.125, 0.130, 0.135, 0.140,0.145, 0.150, 0.155, 0.160, 0.165, 0.170, 0.175, 0.180, 0.185, 0.190,0.195, 0.200, 0.205, 0.210, 0.215, 0.220, 0.225, 0.230, 0.235, 0.240,0.245, 0.250, 0.255, 0.260, 0.265, 0.270, 0.275, 0.280, 0.285, 0.290,0.295, 0.300, 0.305, 0.310, 0.315, 0.320, 0.325, 0.330, 0.335, 0.340,0.345, 0.350, 0.355, 0.360, 0.365, 0.370, 0.375, 0.380, 0.385, 0.390,0.395, 0.400, 0.405, 0.410, 0.415, 0.420, 0.425, 0.430, 0.435, 0.440,0.445, 0.450, 0.455, 0.460, 0.465, 0.470, 0.475, 0.480, 0.485, 0.490,0.495, 0.500, 0.505, 0.510, 0.515, 0.520, 0.525, 0.530, 0.535, 0.540,0.545, 0.550, 0.555, 0.560, 0.565, 0.570, 0.575, 0.580, 0.585, 0.590,0.595, 0.600, 0.605, 0.610, 0.615, 0.620, 0.625, 0.630, 0.635, 0.640,0.645, 0.650, 0.655, 0.660, 0.665, 0.666, 0.667, or 0.670.

The subscript d in the chemical formula Li_(a)Ni_(1-b-c)Co_(b)M_(c)O_(d)represents the relative amount of O (oxygen) in the electrode activematerials. In general, the amount of O can vary from O-rich toO-deficient. For example, d may be from about 1.9 to about 2.1 ingeneral, or from 1.95 to 2.05, from 1.9 to 2.0, from 1.95 to 2.05, from2.0 to 2.05, or from 2.05 to 2.1. In some cases, d may be or may beabout 1.9, 1.905, 1.91, 1.915, 1.92, 1.925, 1.93, 1.935, 1.94, 1.945,1.95, 1.955, 1.96, 1.965, 1.97, 1.975, 1.98, 1.985, 1.99, 1.995, 2,2.005, 2.01, 2.015, 2.02, 2.025, 2.03, 2.035, 2.04, 2.045, 2.05, 2.055,2.06, 2.065, 2.07, 2.075, 2.08, 2.085, 2.09, 2.095, 2.1.

The subscript 1-b-c in the chemical formulaLi_(a)Ni_(1-b-c)Co_(b)M_(c)O_(d) represents the relative amount of Ni(nickel) in the electrode active materials. In general, the amount of Nican vary from relatively low to relatively high, though the relativeamount of Ni may be dependent upon the amounts of Co and metals and/ornon-metals M in the electrode active materials. For example, 1-b-c maybe from about 1 to about 0.5 or from 1 to 0.33. In some cases, 1-b-c maybe or may be about 0.330, 0.333, 0.334, 0.335, 0.340, 0.345, 0.350,0.355, 0.360, 0.365, 0.370, 0.375, 0.380, 0.385, 0.390, 0.395, 0.400,0.405, 0.410, 0.415, 0.420, 0.425, 0.430, 0.435, 0.440, 0.445, 0.450,0.455, 0.460, 0.465, 0.470, 0.475, 0.480, 0.485, 0.490, 0.495, 0.500,0.505, 0.510, 0.515, 0.520, 0.525, 0.530, 0.535, 0.540, 0.545, 0.550,0.555, 0.560, 0.565, 0.570, 0.575, 0.580, 0.585, 0.590, 0.595, 0.600,0.605, 0.610, 0.615, 0.620, 0.625, 0.630, 0.635, 0.640, 0.645, 0.650,0.655, 0.660, 0.665, 0.670, 0.675, 0.680, 0.685, 0.690, 0.695, 0.700,0.705, 0.710, 0.715, 0.720, 0.725, 0.730, 0.735, 0.740, 0.745, 0.750,0.755, 0.760, 0.765, 0.770, 0.775, 0.780, 0.785, 0.790, 0.795, 0.800,0.805, 0.810, 0.815, 0.820, 0.825, 0.830, 0.835, 0.840, 0.845, 0.850,0.855, 0.860, 0.865, 0.870, 0.875, 0.880, 0.885, 0.890, 0.895, 0.900,0.905, 0.910, 0.915, 0.920, 0.925, 0.930, 0.935, 0.940, 0.945, 0.950,0.955, 0.960, 0.965, 0.970, 0.975, 0.980, 0.985, 0.990, 0.995, or 1.000.

The electrode active materials may be in or prepared in a powder form,such as comprising individual secondary particles having cross-sectionaldimensions (e.g., diameters) of from about 500 nm to about 30 μm. Forexample, the cross-sectional dimensions may be from 500 nm to 1.0 μm,from 1.0 μm to 2.5 μm, from 2.5 μm to 5.0 μm, from 5.0 μm to 7.5 μm,from 7.5 μm to 10 μm, from 10 μm to 15 μm, from 15 μm to 20 μm, or from20 μm to 30 μm. The electrode active material may exhibit a tappeddensity of from about 2.0 g·cm⁻³ to about 3.5 g·cm⁻³, such as from 2.0g·cm⁻³ to 2.1 g·cm⁻³, from 2.1 g·cm⁻³ to 2.2 g·cm⁻³, from 2.2 g·cm⁻³ to2.3 g·cm⁻³, from 2.3 g·cm⁻³ to 2.4 g·cm⁻³, from 2.4 g·cm⁻³ to 2.5g·cm⁻³, from 2.5 g·cm⁻³ to 2.6 g·cm⁻³, from 2.6 g·cm⁻³ to 2.7 g·cm⁻³,from 2.7 g·cm⁻³ to 2.8 g·cm⁻³, from 2.8 g·cm⁻³ to 2.9 g·cm⁻³, from 2.9g·cm⁻³ to 3.0 g·cm⁻³, from 3.0 g·cm⁻³ to 3.1 g·cm⁻³, from 3.1 g·cm⁻³ to3.2 g·cm⁻³, from 3.2 g·cm⁻³ to 3.3 g·cm⁻³, from 3.3 g·cm⁻³ to 3.4g·cm⁻³, or from 3.4 g·cm⁻³ to 3.5 g·cm⁻³.

The electrode active materials may exhibit good operational lifetime,such as where a specific energy degradation after 500 cycles is lessthan or about 20%, less than or about 15%, or less than or about 10%. Insome cases, the specific energy degradation after 1000 cycles may beless than or about 20%, less than or about 15%, or less than or about10%. In some cases, the specific energy degradation after 100 cycles maybe less than or about 10%, less than or about 5%, or less than or about2.5%.

Cathodes

The electrode active materials described herein can be cathode activematerials and useful as cathodes (positive electrodes). FIG. 1 providesa schematic illustration of an example cathode 100, which comprises acathode current collector 105 and a cathode active material 110. Cathodecurrent collector 105 may be any suitable current collector, such asthose used in the art. In some examples, the cathode current collector105 may comprise aluminum (e.g., an aluminum foil). Cathode activematerial 110 may comprise any of the electrode active materialsdescribed herein, such as those having the general chemical formulaLi_(a)Ni_(1-b-c)Co_(b)M_(c)O_(d) described above.

Depending on the cathode configuration, the cathode active material 110may have any suitable dimensions or mass. The electrode active materialof cathode active material 110 may optionally be mixed with binders orconductive additives, as known in the art.

Electrochemical Cells

The electrode active materials, cathode active materials, and cathodesdescribed herein can be useful in electrochemical cells and batteries.FIG. 2 provides a schematic illustration of an example electrochemicalcell 200, which comprises a cathode current collector 205, a cathodeactive material 210, an anode current collector 215, an anode activematerial 220, and a separator 225.

The cathode current collector 205 may comprise aluminum, for example.The cathode active material 210 may correspond to any of the electrodeactive materials described herein. The cathode active 210 material maybe mixed with a binder, a conductive additive, a liquid or a solidelectrolyte, etc.

The anode current collector 215 may comprise copper. In some cases, theanode current collector 215 may not be used. Example materials for theanode active material 220 may include, but is not limited to, graphite,carbon, silicon, lithium titanate (Li₄Ti₅O₁₂), tin, antimony, zinc,phosphorous, lithium, or a combination thereof. The anode activematerial 220 may be mixed with a binder, a conductive additive, a liquidor a solid electrolyte, etc.

The separator 225 may be any suitable non-reactive material. Exampleseparators may be polymeric membranes like polypropylene, poly(methylmethacrylate), or polyacrylonitrile, or may be solid or ceramicelectrolytes. The separator 225 may include (e.g., have pores filledwith) an electrolyte or may function as an electrolyte itself, which maybe used to conduct ions back and forth between the cathode activematerial 210 and the anode active material 220. Example electrolytes maybe or include an organic solvent, such as ethylene carbonate, dimethylcarbonate, or diethyl carbonate, or solid or ceramic electrolytes.Electrolytes may include dissolved lithium salts, such as LiPF₆, LiBF₄,or LiClO₄, and other additives.

Methods

The Li_(a)Ni_(1-b-c)Co_(b)M_(c)O_(d) materials may be synthesizedthrough metal co-precipitation and lithiation calcination. First,dissolvable salts of nickel, cobalt, and M, including but not limitedto, nitrates, chlorides, acetates, sulfates, oxalates, and a combinationthereof, are mixed to make an aqueous solution with appropriate metalmolar ratios. The concentration of the mixed-metal ion aqueous solutionmay be from 0.1 mol·L⁻¹ to 3.0 mol·L⁻¹. The mixed-metal ion aqueoussolution is pumped into a tank reactor at a controlled rate under anon-oxidizing gaseous atmosphere. An aqueous solution of sodiumhydroxide, potassium hydroxide, sodium carbonate, potassium carbonate,and a combination thereof, at 0.2 mol·L⁻¹ to 10 mol·L⁻¹ is separatelypumped into the tank reactor to maintain a pH of 8.0 to 12.5. Achelating agent, for example an aqueous solution of ammonium hydroxide,is also pumped into the tank reactor to maintain an appropriateconcentration of the chelating agent inside the tank reactor. Theco-precipitation reaction takes place at a controlled temperature of 30°C. to 80° C.

Subsequently, a precursor P is obtained through washing, filtering, anddrying of the material from the tank reactor and mixed with a lithiumsalt and an additive material X at appropriate molar ratios. The lithiumsalt comprises a lithium carbonate, a lithium hydroxide, a lithiumacetate, a lithium oxide, a lithium oxalate, and a combination thereof.The additive material X comprises salts of M, including but not limitedto, oxides, carbonates, nitrates, acetates, oxalates, hydroxides,fluorides, isopropoxides, and a combination thereof. The mixed precursorP, lithium salt, and additive material X is calcined at 600° C. to 1000°C. under a flowing gaseous atmosphere of an oxygen content from 21%(air) to 100% (pure oxygen) to obtain the lithiated oxide L.

In some examples, the lithiated oxide L is the final product,Li_(a)Ni_(1-b-c)Co_(b)M_(c)O_(d). Optionally, the lithiated oxide L isfurther subject to a surface treatment. During the surface treatment,the lithiated oxide L is mixed with a liquid comprising deionized water,boric acid, phosphoric acid, ethanol, isopropanol, and a combinationthereof.

After drying, the lithiated oxide L is mixed with a lithium salt and anadditive material Y at appropriate molar ratios. The lithium saltcomprises a lithium carbonate, a lithium hydroxide, a lithium acetate, alithium oxide, a lithium oxalate, and a combination thereof. Theadditive material Y comprises salts of M, including but not limited to,oxides, carbonates, nitrates, acetates, oxalates, hydroxides, fluorides,isopropoxides, and a combination thereof.

The mixed lithiated oxide L, lithium salt, and additive material Y issubsequently calcined at elevated temperature, optionally under aflowing gaseous atmosphere of an oxygen content from 21% (air) to 100%(pure oxygen), to obtain the final product,Li_(a)Ni_(1-b-c)Co_(b)M_(c)O_(d).

The synthesis of Li_(a)Ni_(1-b-c)Co_(b)M_(c)O_(d) may be similar to theestablished production methods, but also provides a series ofadvantages: (i) a precise control of metal co-precipitation of nickeland other metals and/or non-metals at appropriate molar ratios thatenables homogenous mixing at the atomic scale, (ii) a precise control ofmetal co-precipitation and lithiation calcination that enables finetuning of the morphology and microstructure of the material secondaryand primary particles, and (iii) an optional surface treatment thatreduces residual lithium species and enhances surface stability of thematerial. It will be appreciated that the properties of lithiumtransition-metal layered oxides are extremely sensitive to theirsynthesis conditions. The synthesis described is useful for enabling thehigh specific energy, high voltage, high rate capability, longoperational lifetime, and desirable safety ofLi_(a)Ni_(1-b-c)Co_(b)M_(c)O_(d).

The invention may be further understood by the following non-limitingexamples.

Example 1

Low-cobalt cathode active materials comprisingLiNi_(0.9)Co_(0.05)Mn_(0.05)O₂, LiNi_(0.9)Co_(0.05)Al_(0.05)O₂, andLiNi_(0.9)Co_(0.04)Mn_(0.04)Al_(0.01)Mg_(0.01)O₂ were prepared accordingto the methods described herein. Dissolvable salts of nickel, cobalt,manganese, aluminum, and magnesium were used to make aqueous solutionsof varying molar ratios at 2.0 mol·L⁻¹. The mixed-metal ion aqueoussolution was pumped into a tank reactor at a controlled rate undernitrogen atmosphere. An aqueous solution of potassium hydroxide at 6.0mol·L⁻¹ and ammonium hydroxide at 1.0 mol·L⁻¹ was separately pumped intothe tank reactor to maintain a pH of 11.5±0.5. The co-precipitationreaction took place at 50±5° C. Subsequently, precursors comprisingNi_(0.9)Co_(0.05)Mn_(0.05)(OH)₂, Ni_(0.9)Co_(0.05)Al_(0.05)(OH)₂, andNi_(0.9)Co_(0.04)Mn_(0.04)Al_(0.01)Mg_(0.01)(OH)₂ were obtained throughwashing, filtering, and drying and mixed with lithium hydroxide at amolar ratio of 1:1.03±0.02. The mixed precursor and lithium hydroxidewas calcinated at 750±20° C. for 17.5±7.5 h under an oxygen atmosphereof a 2.75±2.25 liter per minute flow rate to obtainLiNi_(0.9)Co_(0.05)Mn_(0.05)O₂, LiNi_(0.9)Co_(0.05)Al_(0.05)O₂, andLiNi_(0.9)Co_(0.04)Mn_(0.04)Al_(0.01)Mg_(0.01)O₂. It will be appreciatedthat the lithium and oxygen contents in these chemical compositions arebased on stoichiometry, but the lithium and oxygen contents may deviatefrom their stoichiometric values.

FIG. 3 shows the X-ray diffraction (XRD) patterns ofLiNi_(0.9)Co_(0.05)Mn_(0.05)O₂, LiNi_(0.9)Co_(0.05)Al_(0.05)O₂, andLiNi_(0.9)Co_(0.04)Mn_(0.04)Al_(0.01)Mg_(0.01)O₂. At the bulk level, allmaterials exhibited an R3m layered structure (rhombohedral structure)with a non-significant amount of secondary (impurity) structures.However, local secondary structures can be found in some examples withinthe surface region of a secondary particle. The local secondary phasesare, in some examples, generated through lithiation calcination due tovarying synthesis conditions and provide desirable material propertiesincluding, but not limited to, high specific energy, high voltage, highrate capability, long operational lifetime, and good safety. The localsecondary structures are, in some examples, generated through apost-calcination surface treatment and reduce the amount of surfaceresidual lithium species and increase cycle and thermal stability of thecathode material.

FIG. 4, FIG. 5, and FIG. 6 show the scanning electron microscopy (SEM)images of LiNi_(0.9)Co_(0.05)Mn_(0.05)O₂,LiNi_(0.9)Co_(0.05)Al_(0.05)O₂, andLiNi_(0.9)Co_(0.04)Mn_(0.04)Al_(0.01)Mg_(0.01)O₂, respectively. All thematerials comprised a plurality of particles termed as “secondaryparticles” of an average particle size of 8 μm to 15 μm. In someexamples, the secondary particle size varies from 15 μm to 30 μm. Insome examples, the secondary particle size varies from 7.5 μm to 15 μm.In some examples, the secondary particle size varies from 2.5 μm to 7.5μm. In some examples, the secondary particle size varies from 500 nm to2.5 μm. In some examples, the plurality of secondary particles aresubstantially monodisperse. In some examples, the plurality of secondaryparticles are polydisperse, comprising a fraction of secondary particlesof at least an order of magnitude larger size than another fraction ofsecondary particles. In some examples, the plurality of secondaryparticles are substantially spherical in shape. In FIG. 4, FIG. 5, andFIG. 6, a secondary particle further comprised a plurality of particlestermed as “primary particles” of an average particle size of 100 nm to500 nm. A secondary particle may comprise 1 to 100,000,000 or moreprimary particles. In some examples, the primary particle size variesfrom 10 nm to 100 nm. In some examples, the primary particle size variesfrom 100 nm to 1000 nm. In some examples, the primary particle sizevaries from 1 μm to 10 μm. In some examples, the plurality of primaryparticles are substantially monodisperse. In some examples, a secondaryparticle comprises one primary particle, and the term “single-crystal”is used to describe this particle morphology.

The cathode active materials exhibited a tapped density of about 2.5g·cm⁻³ to 2.6 g·cm⁻³. The cathode active material was formed into acomposite cathode electrode by depositing a slurry of the cathode activematerial in N-Methyl-2-Pyrrolidone onto an aluminum foil currentcollector and allowing the solvent to evaporate. The areal capacityloading of the cathode active material is about 2.0 mAh·cm⁻². Thecathode was assembled into an electrochemical cell with either a lithiummetal anode or a graphite anode, a separator comprising a blend ofpolypropylene and polyethylene soaked with a nonaqueous carbonate-basedelectrolyte comprising 1.0 molar LiPF₆ in a solvent mixture of ethylenecarbonate and ethyl methyl carbonate (3:7 by weight) with an additive ofvinylene carbonate (2% by weight). Voltage profiles were obtained forcharging and discharging the electrochemical cell.

FIG. 7 shows the galvanostatic charge-discharge voltage profiles ofLiNi_(0.9)Co_(0.05)Mn_(0.05)O₂, LiNi_(0.9)Co_(0.05)Al_(0.05)O₂, andLiNi_(0.9)Co_(0.04)Mn_(0.04)Al_(0.01)Mg_(0.01)O₂ in lithium-ion cellspaired with lithium metal. All lithium-ion cells were cycled between 2.8V and 4.4 V vs. Li⁺/Li at ambient temperature (25° C.).LiNi_(0.9)Co_(0.05)Mn_(0.05)O₂ delivered a specific energy of 830Wh·kg⁻¹ at the first C/10 cycle with a Coulombic efficiency of 86%, anda specific energy of 865 Wh·kg⁻¹ at the fourth C/10 cycle.LiNi_(0.9)Co_(0.05)Al_(0.05)O₂ delivered a specific energy of 826Wh·kg⁻¹ at the first C/10 cycle with a Coulombic efficiency of 88%, anda specific energy of 850 Wh·kg⁻¹ at the fourth C/10 cycle.LiNi_(0.9)Co_(0.04)Mn_(0.04)Al_(0.01)Mg_(0.01)O₂ delivered a specificenergy of 789 Wh·kg⁻¹ at the first C/10 cycle with a Coulombicefficiency of 84%, and a specific energy of 823 Wh·kg⁻¹ at the fourthC/10 cycle.

FIG. 8 shows the discharge voltage profiles (upper) and evolution ofspecific energy as a function of cycle number (lower) ofLiNi_(0.9)Co_(0.05)Mn_(0.05)O₂, LiNi_(0.9)Co_(0.05)Al_(0.05)O₂, andLiNi_(0.9)Co_(0.04)Mn_(0.04)Al_(0.01)Mg_(0.01)O₂ in lithium-ion cellspaired with graphite. All lithium-ion cells were cycled between 2.5 Vand 4.2 V vs. graphite at ambient temperature (25° C.), and the datashown excluded formation cycles. LiNi_(0.9)Co_(0.05)Mn_(0.05)O₂delivered a specific energy of 752 Wh·kg⁻¹ at C/3 rate and retained 80%specific energy after 465 charge-discharge cycles at a C/2 charge rateand a 1 C discharge rate. LiNi_(0.9)Co_(0.05)Al_(0.05)O₂ delivered aspecific energy of 734 Wh·kg⁻¹ at C/3 rate and retained 80% specificenergy after 523 charge-discharge cycles at a C/2 charge rate and a 1 Cdischarge rate. LiNi_(0.9)Co_(0.04)Mn_(0.04)Al_(0.01)Mg_(0.01)O₂delivered a specific energy of 694 Wh·kg⁻¹ at C/3 rate and retained 80%specific energy after 982 charge-discharge cycles at a C/2 charge rateand a 1 C discharge rate.

Example 2

Cobalt-free cathode active materials comprisingLiNi_(0.9)Mn_(0.05)Al_(0.05)O₂ and LiNi_(0.9)Mn_(0.05)Mg_(0.05)O₂ wereprepared according to the methods described herein. Dissolvable salts ofnickel, manganese, aluminum, and magnesium are used to make aqueoussolutions of varying molar ratios at 2.0 mol·L⁻¹. The mixed-metal ionaqueous solution was pumped into a tank reactor at a controlled rateunder nitrogen atmosphere. An aqueous solution of potassium hydroxide at6.0 mol·L⁻¹ and ammonium hydroxide at 1.0 mol·L⁻¹ was separately pumpedinto the tank reactor to maintain a pH of 11.5±0.5. The co-precipitationreaction took place at 50±5° C. Subsequently, precursors comprisingNi_(0.9)Mn_(0.05)Al_(0.05)(OH)₂ and Ni_(0.9)Mn_(0.05)Mg_(0.05)(OH)₂ wereobtained through washing, filtering, and drying and mixed with lithiumhydroxide at a molar ratio of 1:1.03±0.02. The mixed precursor andlithium hydroxide was calcinated at 750±20° C. for 17.5±7.5 h under anoxygen atmosphere of a 2.75±2.25 liter per minute flow rate to obtainLiNi_(0.9)Mn_(0.05)Al_(0.05)O₂ and LiNi_(0.9)Mn_(0.05)Mg_(0.05)O₂. Itwill be appreciated that the lithium and oxygen contents in thesechemical compositions are based on stoichiometry, but the lithium andoxygen contents may deviate from their stoichiometric values.

FIG. 3 shows the X-ray diffraction (XRD) patterns ofLiNi_(0.9)Mn_(0.05)Al_(0.05)O₂ and LiNi_(0.9)Mn_(0.05)Mg_(0.05)O₂. Atthe bulk level, all materials exhibited an R3m layered structure(rhombohedral structure) with a non-significant amount of secondary(impurity) structures. FIG. 9 shows the scanning electron microscopy(SEM) images of LiNi_(0.9)Mn_(0.05)Al_(0.05)O₂. The material comprised aplurality of secondary particles of an average particle size of 8 μm to15 μm. In FIG. 9, a secondary particle further comprises a plurality ofprimary particles of an average particle size of 100 nm to 500 nm.

The cathode active materials exhibited a tapped density of about 2.5g·cm⁻³ to 2.6 g·cm⁻³. The cathode active material was formed into acomposite cathode electrode by depositing a slurry of the cathode activematerial in N-Methyl-2-Pyrrolidone onto an aluminum foil currentcollector and allowing the solvent to evaporate. The areal capacityloading of the cathode active material was around 2.0 mAh·cm⁻². Thecathode was assembled into an electrochemical cell with either a lithiummetal anode or a graphite anode, a separator comprising a blend ofpolypropylene and polyethylene soaked with a nonaqueous carbonate-basedelectrolyte comprising 1.0 molar LiPF₆ in a solvent mixture of ethylenecarbonate and ethyl methyl carbonate (3:7 by weight) with an additive ofvinylene carbonate (2% by weight). Voltage profiles were obtained forcharging and discharging the electrochemical cell.

FIG. 10 shows the galvanostatic charge-discharge voltage profiles ofLiNi_(0.9)Mn_(0.05)Al_(0.05)O₂ and LiNi_(0.9)Mn_(0.05)Mg_(0.05)O₂ inlithium-ion cells paired with lithium metal. All lithium-ion cells werecycled between 2.8 V and 4.4 V vs. Li⁺/Li at ambient temperature (25°C.). LiNi_(0.9)Mn_(0.05)Al_(0.05)O₂ delivered a specific energy of 823Wh·kg⁻¹ at the first C/10 cycle with a Coulombic efficiency of 86%, anda specific energy of 839 Wh·kg⁻¹ at the fourth C/10 cycle.LiNi_(0.9)Mn_(0.05)Mg_(0.05)O₂ delivered a specific energy of 727Wh·kg⁻¹ at the first C/10 cycle with a Coulombic efficiency of 80%, anda specific energy of 752 Wh·kg⁻¹ at the fourth C/10 cycle.

FIG. 11 shows the discharge voltage profiles (upper) and evolution ofspecific energy as a function of cycle number (lower) ofLiNi_(0.9)Mn_(0.05)Al_(0.05)O₂ and LiNi_(0.9)Mn_(0.05)Mg_(0.05)O₂ inlithium-ion cells paired with graphite. All lithium-ion cells werecycled between 2.5 V and 4.2 V vs. graphite at ambient temperature (25°C.), and the data shown excluded formation cycles.LiNi_(0.9)Mn_(0.05)Al_(0.05)O₂ delivered a specific energy of 695Wh·kg⁻¹ at C/3 rate and retained 80% specific energy after 862charge-discharge cycles at a C/2 charge rate and a 1 C discharge rate.LiNi_(0.9)Mn_(0.05)Mg_(0.05)O₂ delivered a specific energy of 635Wh·kg⁻¹ at C/3 rate and retained 80% specific energy after 485charge-discharge cycles at a C/2 charge rate and a 1 C discharge rate.

Example 3

The compositions described above in Example 1 and Example 2 were formedinto coin half battery cells with lithium metal as the counter electrodefor further evaluation.

FIG. 12 shows dQ·dV⁻¹ curves of LiNi_(0.90)Co_(0.05)Mn_(0.05)O₂ (blue),LiNi_(0.90)Co_(0.05)Al_(0.05)O₂ (red),LiNi_(0.90)Co_(0.04)Mn_(0.04)Al_(0.01)Mg_(0.01)O₂ (green), andLiNi_(0.90)Mn_(0.05)Al_(0.05)O₂ (gray) in coin half battery cells (vs.Li metal) at 25° C. during C/10 formation cycles.LiNi_(0.90)Mn_(0.05)Al_(0.05)O₂ shows a dQ·dV⁻¹ curve minimum (e.g.,lowest negative peak or nadir) during discharge at a voltage of above4.20 V vs. Li⁺/Li, distinctively higher than cobalt-containinghigh-nickel layered oxide cathode materials. Specifically,LiNi_(0.90)Mn_(0.05)Al_(0.05)O₂ exhibited a minimum of −580 mAh·g⁻¹V⁻¹at 4.22 V vs. Li⁺/Li during discharge at C/10 rate.LiNi_(0.90)Co_(0.05)Mn_(0.05)O₂ exhibited a minimum of −740 mAh·g⁻¹V⁻¹at 4.17 V vs. Li⁺/Li during discharge at a C/10 rate.LiNi_(0.90)Co_(0.05)Al_(0.05)O₂ exhibited a minimum of −420 mAh·g⁻¹V⁻¹at 4.19 V vs. Li⁺/Li during discharge at a C/10 rate.LiNi_(0.90)Co_(0.04)Mn_(0.04)Al_(0.01)Mg_(0.01)O₂ exhibited a minimum of−600 mAh·g⁻¹V⁻¹ at 4.18V vs. Li⁺/Li during discharge at a C/10 rate.

To calculate the dQ·dV⁻¹ plots, lithium metal coin cells were cycled atC/10 rate within 2.8 V and 4.4 V vs. Li⁺/Li. The cycling data used forcalculating the dQ/dV curves are separated by 0.02 V steps. The dQ/dVvalue at each voltage is calculated by the formula in Eq. 1. The charge,Q₂, in Eq. 1 is the total charge at the voltage of interest, V₂, withthe proceeding data point at voltage V₁ and total charge for that chargeor discharge cycle at Q₁. Since data used for dQ/dV calculation isacquired every 0.02 V, ΔV is always 0.02 V, with the unit mAh·g⁻¹V⁻¹.The voltage step of 0.02 V between acquired data points prevents noisefrom impacting the magnitude of the mAh·g⁻¹V⁻¹, which can increase tovery large values when ΔV is set to small values.

$\begin{matrix}{\frac{dQ}{dV} = {\frac{Q_{2} - Q_{1}}{V_{2} - V_{1}} = \frac{\Delta Q}{\Delta V}}} & {{Eq}.\mspace{14mu} 1}\end{matrix}$

Then data points (x, y) can be plotted with x=½(V₁+V₂) and

${y = \frac{Q_{2} - Q_{1}}{V_{2} - V_{1}}}.$

FIG. 13 shows dQ·dV⁻¹ curves of LiNi_(0.90)Co_(0.05)Mn_(0.05)O₂,LiNi_(0.90)Co_(0.05)Al_(0.05)O₂,LiNi_(0.90)Co_(0.04)Mn_(0.04)Al_(0.01)Mg_(0.01)O₂, andLiNi_(0.90)Mn_(0.05)Al_(0.05)O₂ in coin half battery cells (vs. Limetal) at 25° C. during C/3 cycles. It will be appreciated that sincethese cycles were done at C/3 rate, the dQ·dV⁻¹ minimum during dischargewas shifted to slightly lower voltages; it also shifts to lower voltageson charge-discharge cycling. Nevertheless,LiNi_(0.90)Mn_(0.05)Al_(0.05)O₂ exhibited the dQ·dV⁻¹ minimum atconsistently higher voltages during discharge at C/3 rate as cyclingproceeds, in comparison with those of LiNi_(0.90)Co_(0.05)Mn_(0.05)O₂,LiNi_(0.90)Co_(0.05)Al_(0.05)O₂, andLiNi_(0.90)Co_(0.04)Mn_(0.04)Al_(0.01)Mg_(0.01)O₂, during discharge atC/3 rate as cycling proceeds.

FIG. 14 shows Rietveld refinement results of the X-ray diffraction (XRD)patterns of pristine LiNi_(0.90)Co_(0.05)Mn_(0.05)O₂ (NCM),LiNi_(0.90)Co_(0.05)Al_(0.05)O₂ (NCA),LiNi_(0.90)Co_(0.04)Mn_(0.04)Al_(0.01)Mg_(0.01)O₂ (NCMAM), andLiNi_(0.90)Mn_(0.05)Al_(0.05)O₂ (NMA). After lithiation calcination, thefour cathode materials exhibit a well-defined hexagonal latticestructure with the R3m space group. Li/Ni mixing inLiNi_(0.90)Co_(0.05)Mn_(0.05)O₂, LiNi_(0.90)Co_(0.05)Al_(0.05)O₂,LiNi_(0.90)Co_(0.04)Mn_(0.04)Al_(0.01)Mg_(0.01)O₂, andLiNi_(0.90)Mn_(0.05)Al_(0.05)O₂ is 3.3%, 1.4%, 2.6%, and 3.0%,respectively. Note that cobalt-free LiNi_(0.90)Mn_(0.05)Al_(0.05)O₂ doesnot show much higher lithium/nickel mixing than the cobalt-bearingcathodes.

FIG. 15 shows cross-sectional scanning electron microscopy(SEM)/energy-dispersive X-ray spectroscopy (EDX) images ofLiNi_(0.90)Co_(0.05)Mn_(0.05)O₂ (NCM), LiNi_(0.90)Co_(0.05)Al_(0.05)O₂(NCA), LiNi_(0.90)Co_(0.04)Mn_(0.04)Al_(0.01)Mg_(0.01)O₂ (NCMAM), andLiNi_(0.90)Mn_(0.05)Al_(0.05)O₂ (NMA), showing elemental distribution ofthe four cathode materials after calcination. This is particularlyimportant for aluminum, since aluminum substitution via calcination canlead to substantial uncontrolled compositional heterogeneity and phasesegregation at large concentrations (5 mol % here). An example is givenbelow in Comparative Example 3.

FIG. 16 compares the rate capability of LiNi_(0.90)Co_(0.05)Mn_(0.05)O₂(NCM), LiNi_(0.90)Co_(0.05)Al_(0.05)O₂ (NCA),LiNi_(0.90)Co_(0.04)Mn_(0.04)Al_(0.01)Mg_(0.01)O₂ (NCMAM), andLiNi_(0.90)Mn_(0.05)Al_(0.05)O₂ (NMA) in coin half battery cells (vs. Limetal) at 25° C. up to a 5 C discharge rate at a constant C/10 chargerate, normalized to their respective specific capacity at C/10 rate.Notably, the fast-discharging performance ofLiNi_(0.90)Mn_(0.05)Al_(0.05)O₂ is very similar to that ofLiNi_(0.90)Co_(0.05)Mn_(0.05)O₂ and LiNi_(0.90)Co_(0.05)Al_(0.05)O₂, instark contrast to LiNi_(0.9)Mn_(0.1)O₂, which suffers from poor ratecapability according to previous published studies. The presence ofaluminum as a counterbalancing cation to manganese suppressinglithium/nickel mixing is believed to be critical for high-nickelLiNi_(1-c1-c2)Mn_(c1)Al_(c2)O₂-based materials in the absence of cobalt.Here, c1 and c2 total to c and may be from 0 to 0.67, for example.

FIG. 17 shows discharge curves of LiNi_(0.90)Co_(0.05)Mn_(0.05)O₂,LiNi_(0.90)Co_(0.05)Al_(0.05)O₂,LiNi_(0.90)Co_(0.04)Mn_(0.04)Al_(0.01)Mg_(0.01)O₂, andLiNi_(0.90)Mn_(0.05)Al_(0.05)O₂ in coin half battery cells (vs. Limetal) at 25° C. up to a 5 C discharge rate at a constant C/10 chargerate.

Long-term cycling of LiNi_(0.90)Co_(0.05)Mn_(0.05)O₂,LiNi_(0.90)Co_(0.05)Al_(0.05)O₂,LiNi_(0.90)Co_(0.04)Mn_(0.04)Al_(0.01)Mg_(0.01)O₂, andLiNi_(0.90)Mn_(0.05)Al_(0.05)O₂ in pouch full battery cells paired withgraphite anodes is shown in FIG. 18. It will be appreciated that FIG. 18compares the retention of specific capacity, not specific energy, offour cathode materials. Data of specific energy retention duringlong-term cycling is described above. After 1000 deep cycles between 2.5and 4.2 V at a C/2-1 C charge-discharge rate and 25° C.,LiNi_(0.90)Co_(0.04)Mn_(0.04)Al_(0.01)Mg_(0.01)O₂ andLiNi_(0.90)Mn_(0.05)Al_(0.05)O₂, with 84% and 82% capacity retention,respectively, notably outperform LiNi_(0.90)Co_(0.05)Mn_(0.05)O₂ (54%)and LiNi_(0.90)Co_(0.05)Al_(0.05)O₂ (62%) and are similar to acommercial LiNi_(0.6)Co_(0.2)Mn_(0.2)O₂ (NMC-622) cathode (80%). Notethat LiNi_(0.90)Co_(0.05)Mn_(0.05)O₂ performs reasonably well in halfbattery cells but becomes the worst in full battery cells.

FIG. 19 shows differential scanning calorimetry (DSC) profiles ofLiNi_(0.90)Co_(0.05)Mn_(0.05)O₂, LiNi_(0.90)Co_(0.05)Al_(0.05)O₂,LiNi_(0.90)Co_(0.04)Mn_(0.04)Al_(0.01)Mg_(0.01)O₂, andLiNi_(0.90)Mn_(0.05)Al_(0.05)O₂. It will be appreciated that DSC canprovide a measure of the thermal-abuse tolerance of cathode activematerials at highly charged states. During experiment preparation, thecathode samples were charged to 220 mAh·g⁻¹ in coin half battery cellsunder C/10 rate after formation cycles, and then 20 mg to 30 mg ofcathode powders were harvested and rinsed with dimethyl carbonate (DMC)inside an argon-filled glovebox. The cathode powder was then dried andmixed with the aforementioned electrolyte (cathode:electrolyte˜6:4 byweight) and sealed tightly in a 100 μL high-pressure stainless steelcrucible with a gold-plated copper seal. The test was conducted from 30°C. to 350° C. with a 1° C.·min⁻¹ heating rate under argon atmospherewithout any weight loss. The calculated heat release was based on theactive cathode mass. To ensure repeatability of the DSC results, atleast three parallel tests were run for each cathode sample. Thetemperatures of the main exothermic event are 222° C., 237° C., 232° C.,and 238° C., while the normalized heat generations are 1858 J g⁻¹, 1835J g⁻¹, 1738 J g⁻¹, and 1755 J g⁻¹ for LiNi_(0.90)Co_(0.05)Mn_(0.05)O₂,LiNi_(0.90)Co_(0.05)Al_(0.05)O₂,LiNi_(0.90)Co_(0.04)Mn_(0.04)Al_(0.01)Mg_(0.01)O₂, andLiNi_(0.90)Mn_(0.05)Al_(0.05)O₂, respectively. These results show thethermal-abuse tolerance of cobalt-free LiNi_(0.90)Mn_(0.05)Al_(0.05)O₂is superior to that of LiNi_(0.90)Co_(0.05)Mn_(0.05)O₂,LiNi_(0.90)Co_(0.05)Al_(0.05)O₂, andLiNi_(0.90)Co_(0.04)Mn_(0.04)Al_(0.01)Mg_(0.01)O₂ at the same degree ofdeep charge.

Example 4

Cobalt-free cathode active materials comprising LiNiO₂ andLiNi_(0.9)Mn_(0.05)Al_(0.05)O₂ were prepared according to the methodsdescribed herein. Dissolvable salts of nickel, manganese, and aluminumwere used to make aqueous solutions of varying molar ratios at 2.0mol·L⁻¹. The mixed-metal ion aqueous solution was pumped into a tankreactor at a controlled rate under nitrogen atmosphere. An aqueoussolution of potassium hydroxide at 6.0 mol·L⁻¹ and ammonium hydroxide at1.0 mol·L⁻¹ was separately pumped into the tank reactor to maintain a pHof 11.5±0.5. The co-precipitation reaction took place at 50±5° C.Subsequently, precursors comprising Ni(OH)₂ andNi_(0.9)Mn_(0.05)Al_(0.05)(OH)₂ were obtained through washing,filtering, and drying and mixed with lithium hydroxide at a molar ratioof 1:1.03±0.02. The mixed precursor and lithium hydroxide was calcinatedat 720±50° C. for 17.5±7.5 h under an oxygen atmosphere of a 2.75±2.25liter per minute flow rate to obtain LiNiO₂ andLiNi_(0.9)Mn_(0.05)Al_(0.05)O₂. It will be appreciated that the lithiumand oxygen contents in these chemical compositions are based onstoichiometry, but the lithium and oxygen contents may deviate fromtheir stoichiometric values.

FIG. 20 shows the scanning electron microscopy (SEM) images of LiNiO₂.The material comprised a plurality of secondary particles of an averageparticle size of 8 μm to 15 μm. In FIG. 20, a secondary particle furthercomprises a plurality of primary particles of an average particle sizeof 50 nm to 200 nm.

The cathode active material exhibited a tapped density of about 2.5g·cm⁻³ to 2.7 g·cm⁻³. The cathode active material was formed into acomposite cathode electrode by depositing a slurry of the cathode activematerial in N-Methyl-2-Pyrrolidone onto an aluminum foil currentcollector and allowing the solvent to evaporate. The areal capacityloading of the cathode active material was 2.4 mAh·cm⁻² to 2.6 mAh·cm⁻².The cathode was assembled into an electrochemical cell with a lithiummetal anode, a separator comprising a blend of polypropylene andpolyethylene soaked with a nonaqueous carbonate-based electrolytecomprising 1.0 molar LiPF₆ in a solvent mixture of ethylene carbonateand ethyl methyl carbonate (3:7 by weight) with an additive of vinylenecarbonate (2% by weight). Galvanostatic voltage profiles were obtainedfor charging and discharging the electrochemical cell.

FIG. 21 shows the galvanostatic charge-discharge voltage profiles ofLiNiO₂ and LiNi_(0.9)Mn_(0.05)Al_(0.05)O₂ in lithium-ion cells pairedwith lithium metal. The LiNiO₂ lithium-ion cells were cycled between 2.8V and 4.35 V vs. Li⁺/Li at ambient temperature (25° C.). TheLiNi_(0.9)Mn_(0.05)Al_(0.05)O₂ lithium-ion cells were cycled between 2.8V and 4.45 V vs. Li⁺/Li at ambient temperature (25° C.). LiNiO₂delivered a specific energy of 919 Wh·kg⁻¹ at the first C/10 cycle witha Coulombic efficiency of 93.5%, and a specific energy of 931 Wh·kg⁻¹ atthe second C/10 cycle. LiNiO₂ delivered a specific energy of 884.5Wh·kg⁻¹ at C/3 rate and 812 Wh·kg⁻¹ at 1 C rate, respectively. Thespecific energy at 1 C rate of LiNO₂ was 87% of the specific energy atC/10 rate. LiNi_(0.9)Mn_(0.05)Al_(0.05)O₂ delivered a specific energy of853 Wh·kg⁻¹ at the first C/10 cycle with a Coulombic efficiency of89.0%, and a specific energy of 860 Wh·kg⁻¹ at the second C/10 cycle.LiNi_(0.9)Mn_(0.05)Al_(0.05)O₂ delivered a specific energy of 811.5Wh·kg⁻¹ at C/3 rate and 754 Wh·kg⁻¹ at 1 C rate, respectively. Thespecific energy at 1 C rate of LiNi_(0.9)Mn_(0.05)Al_(0.05)O₂ was 87.5%of the specific energy at C/10 rate.

Example 5

Cobalt-free cathode active materials comprising LiNiO₂,LiNi_(0.98)Ta_(0.02)O₂, LiNi_(0.98)Zr_(0.02)O₂, andLiNi_(0.98)Mg_(0.02)O₂ were prepared according to the methods describedherein. First, cathode active material precursor comprising Ni(OH)₂ wasprepared using dissolvable salts of nickel in aqueous solutions at 2.0mol·L⁻¹. The aqueous solution was pumped into a tank reactor at acontrolled rate. An aqueous solution of potassium hydroxide at 6.0mol·L⁻¹ and ammonium hydroxide at 1.0 mol·L⁻¹ was separately pumped intothe tank reactor to maintain a pH of 11.75±0.25. The co-precipitationreaction took place at 50±5° C. Subsequently, precursor comprisingNi(OH)₂ was obtained through washing, filtering, and drying. To obtainLiNiO₂, the precursor comprising Ni(OH)₂ was mixed with lithiumhydroxide at a molar ratio of 1:1.02±0.03. The mixed precursor andlithium hydroxide was calcinated at 690±20° C. for 17.5±7.5 h under anoxygen atmosphere of a 2.75±2.25 liter per minute flow rate. To obtainLiNi_(0.98)Ta_(0.02)O₂, LiNi_(0.98)Zr_(0.02)O₂, orLiNi_(0.98)Mg_(0.02)O₂, precursor comprising Ni(OH)₂ was mixed witheither tantalum oxide, zirconium oxide, or magnesium oxide, andadditionally lithium hydroxide at a molar ratio of 0.98:0.02:1.02±0.03.The mixed precursor, either tantalum oxide, zirconium oxide, ormagnesium oxide, and lithium hydroxide was calcinated at 720±30° C. for17.5±7.5 h under an oxygen atmosphere of a 2.75±2.25 liter per minuteflow rate. It will be appreciated that the lithium and oxygen contentsin these chemical compositions are based on stoichiometry, but thelithium and oxygen contents may deviate from their stoichiometricvalues.

The cathode active material exhibited a tapped density of about 2.5g·cm⁻³ to 2.7 g·cm⁻³. The cathode active material was formed into acomposite cathode electrode by depositing a slurry of the cathode activematerial in N-Methyl-2-Pyrrolidone onto an aluminum foil currentcollector and allowing the solvent to evaporate. The areal capacityloading of the cathode active material was around 2.0 mAh·cm⁻². Thecathode was assembled into an electrochemical cell with a lithium metalanode, a separator comprising a blend of polypropylene and polyethylenesoaked with a nonaqueous carbonate-based electrolyte comprising 1.0molar LiPF₆ in a solvent mixture of ethylene carbonate and ethyl methylcarbonate (3:7 by weight) with an additive of vinylene carbonate (2% byweight). Galvanostatic voltage profiles were obtained for charging anddischarging the electrochemical cell.

FIG. 22, FIG. 23, FIG. 24, and FIG. 25 show dQ·dV⁻¹ curves of LiNiO₂,LiNi_(0.98)Ta_(0.02)O₂, LiNi_(0.98)Zr_(0.02)O₂, andLiNi_(0.98)Mg_(0.02)O₂, respectively, in coin half battery cells (vs.lithium metal) at 25° C. during C/10 formation cycles. All lithium-ioncells were cycled between 2.8 V and 4.4 V vs. Li⁺/Li at ambienttemperature (25° C.). All samples show a minimum (e.g., lowest negativepeak or nadir) of at least −900 mAh·g⁻¹V⁻¹ or lower during discharge ata voltage vs. Li⁺/Li of 4.15 V or higher. With a current rate of C/10,LiNiO₂ shows a minimum of −2060 mAh·g⁻¹V⁻¹ in the dQ·dV⁻¹ curve duringdischarge at a voltage of 4.154 V vs. Li⁺/Li. With a current rate ofC/10, LiNi_(0.98)Ta_(0.02)O₂ shows a minimum of −1780 mAh·g⁻¹V⁻¹ in thedQ·dV⁻¹ curve during discharge at a voltage of 4.150 V vs. Li⁺/Li. Witha current rate of C/10, LiNi_(0.98)Zr_(0.020) shows a minimum of −2420mAh·g⁻¹V⁻¹ in the dQ·dV⁻¹ curve during discharge at a voltage of 4.152 Vvs. Li⁺/Li. With a current rate of C/10, LiNi_(0.98)Mg_(0.02)O₂ shows aminimum of −900 mAh·g⁻¹V⁻¹ in the dQ·dV⁻¹ curve during discharge at avoltage of 4.162 V vs. Li⁺/Li.

To calculate the dQ·dV⁻¹ plots, lithium metal coin cells were cycled atC/10 rate within 2.8 and 4.4 V vs. Li⁺/Li. The cycling data used forcalculating the dQ/dV curves are separated by 0.02 V steps. The dQ/dVvalue at each voltage is calculated by the formula in Eq. 1, describedabove. The charge, Q₂, in Eq. 1 is the total charge at the voltage ofinterest, V₂, with the proceeding data point at voltage V₁ and totalcharge for that charge or discharge cycle at Q₁. Since data used fordQ/dV calculation is acquired every 0.02 V, ΔV is always 0.02 V, withthe unit mAh·g⁻¹V⁻¹. The voltage step of 0.02 V between acquired datapoints prevents noise from impacting the magnitude of the mAh·g⁻¹V₁,which can increase to very large values when ΔV is set to small values.The data points (x, y) can be plotted with x=½(V₁+V₂) and y=Q₂−Q₁/V₂−V₁.

Comparative Example 1

A cobalt-free cathode active material comprisingLiNi_(0.9)Mn_(0.05)Al_(0.05)O₂ was prepared according to the methodsdescribed herein. Dissolvable salts of nickel, manganese, and aluminumwere used to make aqueous solutions of varying molar ratios at 2.0mol·L⁻¹. The mixed-metal ion aqueous solution was pumped into a tankreactor at a controlled rate under nitrogen atmosphere. An aqueoussolution of potassium hydroxide at 6.0 mol·L⁻¹ and ammonium hydroxide at1.0 mol·L⁻¹ was separately pumped into the tank reactor to maintain a pHof 11.5±0.5. The co-precipitation reaction took place at 50±5° C.Subsequently, precursor comprising Ni_(0.9)Mn_(0.05)Al_(0.05)(OH)₂ wasobtained through washing, filtering, and drying and mixed with lithiumhydroxide at a molar ratio of 1:1.03±0.07. The mixed precursor andlithium hydroxide was calcinated at 750±20° C. for 17.5±7.5 h under anoxygen atmosphere of a 2.75±2.25 liter per minute flow rate to obtainLiNi_(0.9)Mn_(0.05)Al_(0.05)O₂. It will be appreciated that the lithiumand oxygen contents in these chemical compositions are based onstoichiometry, but the lithium and oxygen contents may deviate fromtheir stoichiometric values.

The cathode active material exhibited a tapped density of about 2.5g·cm⁻³. The cathode active material was formed into a composite cathodeelectrode by depositing a slurry of the cathode active material inN-Methyl-2-Pyrrolidone onto an aluminum foil current collector andallowing the solvent to evaporate. The areal capacity loading of thecathode active material was around 2.0 mAh·cm⁻². The cathode wasassembled into an electrochemical cell with a lithium metal anode, aseparator comprising a blend of polypropylene and polyethylene soakedwith a nonaqueous carbonate-based electrolyte comprising 1.0 molar LiPF₆in a solvent mixture of ethylene carbonate and ethyl methyl carbonate(3:7 by weight) with an additive of vinylene carbonate (2% by weight).Galvanostatic voltage profiles were obtained for charging anddischarging the electrochemical cell.

FIG. 26 shows the galvanostatic charge-discharge voltage profiles(upper) and evolution of specific capacity as a function of cycle number(lower) of LiNi_(0.9)Mn_(0.05)Al_(0.05)O₂ with varying calcinationconditions in lithium-ion cells paired with lithium metal. Alllithium-ion cells were cycled between 2.8 V and 4.4 V vs. Li⁺/Li atambient temperature (25° C.). The differentLiNi_(0.9)Mn_(0.05)Al_(0.05)O₂ were calcined using the sameNi_(0.9)Mn_(0.05)Al_(0.05)(OH)₂ precursor.LiNi_(0.9)Mn_(0.05)Al_(0.05)O₂ calcined at 750° C. with a 0.98lithium/(nickel+manganese+aluminum) ratio for 10 h (left) delivered aspecific capacity of 186 mAh·g⁻¹ at the first cycle at C/10 rate with aCoulombic efficiency of 79%, a specific capacity of 197 mAh·g⁻¹ at thefourth cycle at C/10 rate, and a cycling stability of 69.0% after 100charge-discharge cycles at C/3 rate. LiNi_(0.9)Mn_(0.05)Al_(0.05)O₂calcined at 750° C. with a 1.03 lithium/(nickel+manganese+aluminum)ratio for 15 h (middle) delivered a specific capacity of 203 mAh·g⁻¹ atthe first cycle at C/10 rate with a Coulombic efficiency of 84%, aspecific capacity of 213 mAh·g⁻¹ at the fourth cycle at C/10 rate, and acycling stability of 91.9% after 100 charge-discharge cycles at C/3rate. LiNi_(0.9)Mn_(0.05)Al_(0.05)O₂ calcined at 760° C. with a 1.10lithium/(nickel+manganese+aluminum) ratio for 12 h (right) delivered aspecific capacity of 214 mAh·g⁻¹ at the first cycle at C/10 rate with aCoulombic efficiency of 87%, a specific capacity of 218 mAh·g⁻¹ at thefourth cycle at C/10 rate, and a cycling stability of 34.3% after 100charge-discharge cycles at C/3 rate.

In FIG. 27, LiNi_(0.9)Mn_(0.05)Al_(0.05)O₂ calcined at 750° C. with a0.98 lithium/(nickel+manganese+aluminum) ratio for 10 h (black)exhibited a minimum of −650 mAh·g⁻¹V⁻¹ at 4.19 V vs. Li⁺/Li duringdischarge at C/10 rate. LiNi_(0.9)Mn_(0.05)Al_(0.05)O₂ calcined at 750°C. with a 1.03 lithium/(nickel+manganese+aluminum) ratio for 15 h (gray)exhibited a minimum of −550 mAh·g⁻¹V⁻¹ at 4.22 V vs. Li⁺/Li duringdischarge at C/10 rate. It will be appreciated that theLi_(a)Ni_(1-b-c)Co_(b)M_(c)O_(d) materials show substantially differentelectrochemical properties, including but not limited to, specificenergy, first-cycle Coulombic efficiency, voltage, rate capability,operational lifetime, and safety, synthesized by different calcinationconditions, as demonstrated in this comparative example.

Comparative Example 2

A low-cobalt cathode active material precursor comprisingNi_(0.9)Co_(0.05)Mn_(0.05)(OH)₂ or Ni_(0.9)Co_(0.05)Mn_(0.05)CO₃ wasprepared according to the methods described herein. Dissolvable salts ofnickel, cobalt, and manganese were used to make aqueous solutions ofvarying molar ratios at 0.5 mol·L⁻¹ to 2.0 mol·L⁻¹. The mixed-metal ionaqueous solution was pumped into a tank reactor at a controlled rateunder nitrogen atmosphere. An aqueous solution of potassium hydroxide orsodium carbonate at 1.0 mol·L⁻¹ to 6.0 mol·L⁻¹ and ammonium hydroxide at0.5 mol·L⁻¹ to 2.0 mol·L⁻¹ was separately pumped into the tank reactorto maintain a pH of 8.0 to 12.5. The co-precipitation reaction tookplace at 50±10° C. and the total reactor time varied from 4 h to 48 h.Subsequently, precursor comprising LiNi_(0.9)Mn_(0.05)Al_(0.05)(OH)₂ orNi_(0.9)Co_(0.05)Mn_(0.05)CO₃ was obtained through washing, filtering,and drying of the material from the tank reactor. The precursor wouldthen be used to make the LiNi_(0.9)Co_(0.05)Mn_(0.05)O₂ cathodematerial.

FIG. 28 shows the scanning electron microscopy (SEM) images ofNi_(0.9)Co_(0.05)Mn_(0.05)(OH)₂ or Ni_(0.9)Co_(0.05)Mn_(0.05)CO₃ withvarying co-precipitation conditions. Ni_(0.9)Co_(0.05)Mn_(0.05)(OH)₂precipitated with potassium hydroxide at a pH of 10.75, a temperature of50° C., and a reaction time of 6 h (upper left) exhibited an averageparticle size of 4 μm to 6 μm and a tapped density of 1.4 g·cm⁻³.Ni_(0.9)Co_(0.05)Mn_(0.05)(OH)₂ precipitated with potassium hydroxide ata pH of 10.50, a temperature of 50° C., and a reaction time of 4 h(upper middle) exhibited an average particle size of 1 μm to 10 μm and atapped density of 1.5 g·cm⁻³. Ni_(0.9)Co_(0.05)Mn_(0.05)CO₃ precipitatedwith sodium carbonate at a pH of 8.30, a temperature of 60° C., and areaction time of 6 h (upper right) exhibited an average particle size of6 μm to 10 μm and a tapped density of 1.8 g·cm⁻³.Ni_(0.9)Co_(0.05)Mn_(0.05)(OH)₂ precipitated with potassium hydroxide ata pH of 11.25, a temperature of 50° C., and a reaction time of 12 h(lower left) exhibited an average particle size of 8 μm to 10 μm and atapped density of 2.3 g·cm⁻³. Ni_(0.9)Co_(0.05)Mn_(0.05)(OH)₂precipitated with potassium hydroxide at a pH of 11.25, a temperature of50° C., and a reaction time of 36 h (lower right) exhibited an averageparticle size of 25 μm and a tapped density of 2.5 g·cm⁻³. It will beappreciated that the morphology and microstructure of precipitatedprecursors are largely preserved after lithiation calcination, therebysignificantly affecting the physical and electrochemical properties ofLi_(a)Ni_(1-b-c)Co_(b)M_(c)O_(d). In this comparative example, theaverage particle size, particle size distribution, and tapped densityvaried greatly among precursors precipitated at different conditions,and considerably affected the gravimetric and volumetric energy density,rate capability, and operational lifetime ofLiNi_(0.9)Co_(0.05)Mn_(0.05)O₂ in lithium-ion cells.

Comparative Example 3

Cobalt-free cathode active materials comprising LiNi_(0.95)Mn_(0.05)O₂and LiNi_(0.9)Mn_(0.05)Al_(0.05)O₂ were prepared according to themethods described herein. First, cathode active material precursorcomprising Ni_(0.95)Mn_(0.05)(OH)₂ was prepared using dissolvable saltsof nickel and manganese in aqueous solutions of varying molar ratios at2.0 mol·L⁻¹. The mixed-metal ion aqueous solution was pumped into a tankreactor at a controlled rate under nitrogen atmosphere. An aqueoussolution of potassium hydroxide at 6.0 mol·L⁻¹ and ammonium hydroxide at1.0 mol·L⁻¹ was separately pumped into the tank reactor to maintain a pHof 11.65±0.25. The co-precipitation reaction took place at 50±5° C.Subsequently, precursor comprising Ni_(0.95)Mn_(0.05)(OH)₂ was obtainedthrough washing, filtering, and drying. To obtainLiNi_(0.95)Mn_(0.05)O₂, the precursor comprising Ni_(0.95)Mn_(0.05)(OH)₂was mixed with lithium hydroxide at a molar ratio of 1:1.02±0.03. Themixed precursor and lithium hydroxide was calcinated at 700±20° C. for17.5±7.5 h under an oxygen atmosphere of a 2.75±2.25 liter per minuteflow rate. To obtain LiNi_(0.9)Mn_(0.05)Al_(0.05)O₂, precursorcomprising Ni_(0.95)Mn_(0.05)(OH)₂ was first dry-mixed with aluminumisopropoxide at a molar ratio of 0.95:0.05 via ball milling at 120 rpmfor 24 h, then the precursor mixed with aluminum isopropoxide wasfurther mixed with lithium hydroxide at a molar ratio of 1:1.02±0.03.The mixed precursor, aluminum isopropoxide, and lithium hydroxide wascalcinated at 750±20° C. for 17.5±7.5 h under an oxygen atmosphere of a2.75±2.25 liter per minute flow rate. It will be appreciated that thelithium and oxygen contents in these chemical compositions are based onstoichiometry, but the lithium and oxygen contents may deviate fromtheir stoichiometric values.

The cathode active material exhibited a tapped density of about 2.5g·cm⁻³. The cathode active material was formed into a composite cathodeelectrode by depositing a slurry of the cathode active material inN-Methyl-2-Pyrrolidone onto an aluminum foil current collector andallowing the solvent to evaporate. The areal capacity loading of thecathode active material was around 2.0 mAh·cm⁻². The cathode wasassembled into an electrochemical cell with a lithium metal anode, aseparator comprising a blend of polypropylene and polyethylene soakedwith a nonaqueous carbonate-based electrolyte comprising 1.0 molar LiPF₆in a solvent mixture of ethylene carbonate and ethyl methyl carbonate(3:7 by weight) with an additive of vinylene carbonate (2% by weight).Galvanostatic voltage profiles were obtained for charging anddischarging the electrochemical cell.

FIG. 29 shows the evolution of specific capacity as a function of cyclenumber of LiNi_(0.95)Mn_(0.05)O₂ and LiNi_(0.9)Mn_(0.05)Al_(0.05)O₂ inlithium-ion cells paired with lithium metal. All lithium-ion cells werecycled between 2.8 V and 4.4 V vs. Li⁺/Li at ambient temperature (25°C.). LiNi_(0.95)Mn_(0.05)O₂ delivered a specific capacity of 200 mAh·g⁻¹at the first cycle at C/10 rate, a specific capacity of 202 mAh·g⁻¹ atthe fourth cycle at C/3 rate, and a cycling stability of 88.2% after 100charge-discharge cycles at C/3 rate. LiNi_(0.9)Mn_(0.05)Al_(0.05)O₂prepared using precursor comprising Ni_(0.95)Mn_(0.05)(OH)₂ and drymixing with aluminum isopropoxide delivered a specific capacity of 208mAh·g⁻¹ at the first cycle at C/10 rate, a specific capacity of 202mAh·g⁻¹ at the fifth cycle at C/3 rate, and a cycling stability of 42.9%after 100 charge-discharge cycles at C/3 rate. It will be appreciatedthat the Li_(a)Ni_(1-b-c)Co_(b)M_(c)O_(d) materials show substantiallydifferent electrochemical properties, and may not be stable at allduring electrochemical cycling synthesized by different materialprecursors from co-precipitation, as demonstrated in this comparativeexample.

REFERENCES

-   Kim, J., Lee, H., Cha, H., Yoon, M., Park, M. & Cho, J. Prospect and    Reality of Ni-Rich Cathode for Commercialization. Advanced Energy    Materials, 8, 1702028 (2018).-   Bianchini, M., Roca-Ayats, M., Hartmann, P., Brezesinski, T. &    Janek, J. There and Back Again—The Journey of LiNi02 as A Cathode    Active Material. Angewandte Chemie-International Edition, 58, 2-27    (2019).-   Neigel, T., Schipper, F., Erickson, E. M., Susai, F. A.,    Markovsky, B. & Aurbach, D. Structural and Electrochemical Aspects    of LiNi_(0.8)Co_(0.1)Mn_(0.1)O₂ Cathode Materials Doped by Various    Cations. ACS Energy Letters, 4, 508-516 (2019).-   Li, H., Cormier, M., Zhang, N., Inglis, J., Li, J. & Dahn, J. R. Is    Cobalt Needed in Ni-Rich Positive Electrode Materials for Lithium    Ion Batteries? Journal of the Electrochemical Society, 166,    A429-A439 (2019).-   Ryu, H. H., Park, K. J., Yoon, D. R., Aishova, A., Yoon, C. S. &    Sun, Y. K., Li[Ni_(0.9)Co_(0.09)W_(0.01)]O₂: A New Type of Layered    Oxide Cathode with High Cycling Stability. Advanced Energy    Materials, 9, 1902698 (2019).-   Aishova et al., 2019, “Cobalt-Free High-Capacity Ni-Rich Layered    Li[Ni_(0.9)Mn_(=0.1)]O₂ Cathode,” Advanced Energy Materials,    1903179.-   Zhang et al., 2019, “Cobalt-Free Nickel-Rich Positive Electrode    Materials with a Core-Shell Structure,” Chem. Mater, 31,    10150-10160.-   Mu et al., 2019, “Dopant Distribution in Co-Free High-Energy Layered    Cathode Materials,” Chem. Mater., 31, 9769-9776.-   U.S. Pat. Nos. 5,264,201, 6,677,082, 6,680,143, 6,964,828,    7,078,128, 7,585,43, 7,648,693, 7,985,503, 8,241,791, 8,377,412,    8,426,066, 8,685,565, 8,784,770, 9,412,996.-   U.S. Patent Application Publication Nos. US 2001/0010807, US    2003/0027048, US 2006/0105239, US 2006/0147798, US 2009/0207246, US    2009/0224212, US 2011/0260099, US 2012/0301786, US 2015/0050522, US    2015/0132651, US 2015/0188136, US 2016/0372748, US 2017/0054147, US    2017/0338471, US 2017/0358796, US 2018/0019464, US 2019/0140276, US    2019/0221843.-   PCT International Application Publication No. WO/2018/200631.-   Chinese Patent or Publication Nos. CN101139108A, CN102437323B,    CN103456946B, CN103715409A, CN103943844A, CN104319391A,    CN106257718B, CN108199027A, CN109686970A, CN109904447A,    CN109962223A, CN109970106A.-   Korean Patent or Publication Nos. KR2016023496A, KR1702572B1,    KR102021151B1.

Illustrative Aspects

As used below, any reference to a series of aspects (e.g., “Aspects1-4”) or non-enumerated group of aspects (e.g., “any previous orsubsequent aspect”) is to be understood as a reference to each of thoseaspects disjunctively (e.g., “Aspects 1-4” is to be understood as“Aspects 1, 2, 3, or 4”).

Aspect 1 is an electrode active material comprising:Li_(a)Ni_(1-b-c)Co_(b)M_(c)O_(d), wherein: a is from 0.9 to 1.1, b isfrom 0 to 0.05, c is from 0 to 0.67, d is from 1.9 to 2.1, and M is Mn,Al, Mg, Fe, Cr, B, Ti, Zr, Ga, Zn, V, Cu, Yb, Li, Na, K, F, Ba, Ca, Lu,Y, Nb, Mo, Ru, Rh, Ta, Pr, W, Ir, In, Tl, Sn, Sr, S, P, Cl, Ge, Sb, Er,Te, La, Ce, Nd, Dy, Eu, Sc, Se, Si, Tc, Pd, Pm, Sm, Gd, Tb, Ho, Tm, orany combination of these.

Aspect 2 is an electrode active material comprising:Li_(a)Ni_(1-b-c)Co_(b)M_(c)O_(d), wherein: a is from 0.9 to 1.1, b isfrom 0 to 0.1, c is from 0 to 0.67, d is from 1.9 to 2.1, and M is Mn,Al, Mg, Fe, Cr, B, Ti, Zr, Ga, Zn, V, Cu, Yb, Li, Na, K, F, Ba, Ca, Lu,Y, Nb, Mo, Ru, Rh, Ta, Pr, W, Ir, In, Tl, Sn, Sr, S, P, Cl, Ge, Sb, Er,Te, La, Ce, Nd, Dy, Eu, Sc, Se, Si, Tc, Pd, Pm, Sm, Gd, Tb, Ho, Tm, orany combination of these; and wherein the electrode active materialexhibits or is characterized by a specific energy for a single dischargebetween 5 V and 3 V vs. Li⁺/Li of from 600 Wh·kg⁻¹ to 1000 Wh·kg⁻¹, andexhibits or is characterized by a specific energy for a 1 C dischargerate between 5 V and 3 V vs. Li⁺/Li that is from 80% to 100% of aspecific energy for a C/10 discharge rate between 5 V and 3 V vs. Li⁺/Liat 25° C.

Aspect 3 is an electrode active material comprising:Li_(a)Ni_(1-b-c)Co_(b)M_(c)O_(d), wherein a is from 0.9 to 1.1, b isfrom 0 to 0.05, c is from 0 to 0.67, d is from 1.9 to 2.1, and M is atleast one element selected from the group consisting of Mn, Al, Mg, Fe,Cr, B, Ti, Zr, Ga, Zn, V, Cu, Yb, Li, Na, K, F, Ba, Ca, Lu, Y, Nb, Mo,Ru, Rh, Ta, Pr, W, Ir, In, Tl, Sn, Sr, S, P, Cl, Ge, Sb, Er, Te, La, Ce,Nd, Dy, Eu, Sc, Se, Si, Tc, Pd, Pm, Sm, Gd, Tb, Ho, and Tm; and whereinthe electrode active material exhibits a dQ·dV⁻¹ curve at the secondcharge-discharge formation cycle for a current rate of C/10 having aminimum during discharge at a voltage of from 4.15 V to 4.30 V vs.Li⁺/Li.

Aspect 4 is the electrode active material of any previous or subsequentaspect, wherein M is a combination of Mn and Al; a combination of Mn,Mg, and Al; a combination of Mn and Mg; a combination of Al and Mg; or acombination of Ti, Mg, and Al.

Aspect 5 is the electrode active material of any previous or subsequentaspect, wherein M comprises Fe or Zn or both Fe and Zn.

Aspect 6 is the electrode active material of any previous or subsequentaspect, wherein the active material is free or substantially free of Co.

Aspect 7 is the electrode active material of any previous or subsequentaspect, wherein b is 0 or wherein b is less than 0.01.

Aspect 8 is the electrode active material of any previous or subsequentaspect, wherein a is from 0.9 to 1.

Aspect 9 is the electrode active material of any previous or subsequentaspect, wherein a is from 1 to 1.1.

Aspect 10 is the electrode active material of any previous or subsequentaspect, wherein b is from 0 to 0.01 and wherein c is from 0 to 0.01.

Aspect 11 is the electrode active material of any previous or subsequentaspect, wherein c is from 0.1 to 0.5, from 0.1 to 0.2, or from 0.2 to0.4.

Aspect 12 is the electrode active material of any previous or subsequentaspect, wherein d is from 1.95 to 2.05.

Aspect 13 is the electrode active material of any previous or subsequentaspect, exhibiting or characterized by a tapped density of from 2.0g·cm⁻³ to 3.5 g·cm⁻³.

Aspect 14 is the electrode active material of any previous or subsequentaspect, exhibiting or characterized by a tapped density of from 2.3g·cm⁻³ to 3.0 g·cm⁻³.

Aspect 15 is the electrode active material of any previous or subsequentaspect, exhibiting or characterized by a tapped density of from 2.5g·cm⁻³ to 2.8 g·cm⁻³.

Aspect 16 is the electrode active material of any previous or subsequentaspect, exhibiting or characterized by a specific energy for a singledischarge between 5 V and 3 V vs. Li⁺/Li of from 600 Wh·kg⁻¹ to 1000Wh·kg⁻¹.

Aspect 17 is the electrode active material of any previous or subsequentaspect, exhibiting or characterized by a specific energy for a singledischarge between 5 V and 3 V vs. Li⁺/Li of from 600 Wh·kg⁻¹ to 1000Wh·kg⁻¹ at 25° C.

Aspect 18 is the electrode active material of any previous or subsequentaspect, exhibiting or characterized by a specific energy for a singledischarge between 5 V and 3 V vs. Li⁺/Li of from 700 Wh·kg⁻¹ to 1000Wh·kg⁻¹, from 800 Wh·kg⁻¹ to 1000 Wh·kg⁻¹, or 900 Wh·kg⁻¹ to 1000Wh·kg⁻¹.

Aspect 19 is the electrode active material of any previous or subsequentaspect, exhibiting or characterized by a dQ·dV⁻¹ curve at the secondcharge-discharge formation cycle, for a current rate of C/10, which hasa minimum of −300 mAh·g⁻¹V⁻¹ or lower during discharge at a voltage offrom 4.15 V to 4.30 V vs. Li⁺/Li.

Aspect 20 is the electrode active material of any previous or subsequentaspect, exhibiting or characterized by a dQ·dV⁻¹ curve at the secondcharge-discharge formation cycle for a current rate of C/10 having aminimum during discharge at a voltage of from 4.15 V to 4.30 V vs.Li⁺/Li.

Aspect 21 is the electrode active material of any previous or subsequentaspect, exhibiting or characterized by a dQ·dV⁻¹ curve at the secondcharge-discharge formation cycle for a current rate of C/10 having aminimum during discharge at a voltage of from 4.16 V to 4.30 V vs.Li⁺/Li.

Aspect 22 is the electrode active material of any previous or subsequentaspect, exhibiting or characterized by a dQ·dV⁻¹ curve at the secondcharge-discharge formation cycle for a current rate of C/10 having aminimum during discharge at a voltage of from 4.17 V to 4.30 V vs.Li⁺/Li.

Aspect 23 is the electrode active material of any previous or subsequentaspect, exhibiting or characterized by a dQ·dV⁻¹ curve at the secondcharge-discharge formation cycle for a current rate of C/10 having aminimum during discharge at a voltage of from 4.18 V to 4.30 V vs.Li⁺/Li.

Aspect 24 is the electrode active material of any previous or subsequentaspect, exhibiting or characterized by a dQ·dV⁻¹ curve at the secondcharge-discharge formation cycle for a current rate of C/10 having aminimum during discharge at a voltage of from 4.19 V to 4.30 V vs.Li⁺/Li.

Aspect 25 is the electrode active material of any previous or subsequentaspect, exhibiting or characterized by a dQ·dV⁻¹ curve at the secondcharge-discharge formation cycle for a current rate of C/10 having aminimum during discharge at a voltage of from 4.20 V to 4.30 V vs.Li⁺/Li.

Aspect 26 is the electrode active material of any previous or subsequentaspect, exhibiting or characterized by a dQ·dV⁻¹ curve at the secondcharge-discharge formation cycle for a current rate of C/10 having aminimum during discharge at a voltage of from 4.21 V to 4.30 V vs.Li⁺/Li.

Aspect 27 is the electrode active material of any previous or subsequentaspect, exhibiting or characterized by a dQ·dV⁻¹ curve at the secondcharge-discharge formation cycle for a current rate of C/10 having aminimum during discharge at a voltage of from 4.22 V to 4.30 V vs.Li⁺/Li.

Aspect 28 is the electrode active material of any previous or subsequentaspect, exhibiting or characterized by a dQ·dV⁻¹ curve at the secondcharge-discharge formation cycle for a current rate of C/10 having aminimum during discharge with a magnitude of −300 mAh·g⁻¹V⁻¹ or lower,such as from −300 mAh·g⁻¹V⁻¹ to −3000 mAh·g⁻¹V⁻¹.

Aspect 29 is the electrode active material of any previous or subsequentaspect, exhibiting or characterized by a dQ·dV⁻¹ curve at the secondcharge-discharge formation cycle for a current rate of C/10 having aminimum during discharge with a magnitude of −400 mAh·g⁻¹V⁻¹ or lower.

Aspect 30 is the electrode active material of any previous or subsequentaspect, exhibiting or characterized by a dQ·dV⁻¹ curve at the secondcharge-discharge formation cycle for a current rate of C/10 having aminimum during discharge with a magnitude of −500 mAh·g⁻¹V⁻¹ or lower.

Aspect 31 is the electrode active material of any previous or subsequentaspect, exhibiting or characterized by a dQ·dV⁻¹ curve at the secondcharge-discharge formation cycle for a current rate of C/10 having aminimum during discharge with a magnitude of −600 mAh·g⁻¹V⁻¹ or lower.

Aspect 32 is the electrode active material of any previous or subsequentaspect, exhibiting or characterized by a dQ·dV⁻¹ curve at the secondcharge-discharge formation cycle for a current rate of C/10 having aminimum during discharge with a magnitude of −800 mAh·g⁻¹V⁻¹ or lower.

Aspect 33 is the electrode active material of any previous or subsequentaspect, exhibiting or characterized by a dQ·dV⁻¹ curve at the secondcharge-discharge formation cycle for a current rate of C/10 having aminimum during discharge with a magnitude of −1000 mAh·g⁻¹V⁻¹ or lower.

Aspect 34 is the electrode active material of any previous or subsequentaspect, exhibiting or characterized by a dQ·dV⁻¹ curve at the secondcharge-discharge formation cycle for a current rate of C/10 having aminimum during discharge with a magnitude of −1500 mAh·g⁻¹V⁻¹ or lower.

Aspect 35 is the electrode active material of any previous or subsequentaspect, exhibiting or characterized by a dQ·dV⁻¹ curve at the secondcharge-discharge formation cycle for a current rate of C/10 having aminimum during discharge with a magnitude of −2000 mAh·g⁻¹V⁻¹ or lower.

Aspect 36 is the electrode active material of any previous or subsequentaspect, exhibiting or characterized by a dQ·dV⁻¹ curve at the secondcharge-discharge formation cycle for a current rate of C/10 having aminimum during discharge with a magnitude of −2500 mAh·g⁻¹V⁻¹ or lower.

Aspect 37 is the electrode active material of any previous or subsequentaspect, exhibiting or characterized by a specific energy for a singledischarge between 5 V and 3 V vs. Li⁺/Li at a 1 C discharge rate of from600 Wh·kg⁻¹ to 1000 Wh·kg⁻¹.

Aspect 38 is the electrode active material of any previous or subsequentaspect, exhibiting or characterized by a specific energy for a singledischarge between 5 V and 3 V vs. Li⁺/Li at a C/10 discharge rate offrom 600 Wh·kg⁻¹ to 1000 Wh·kg⁻¹.

Aspect 39 is the electrode active material of any previous or subsequentaspect, exhibiting or characterized by a specific energy after 500charge-discharge cycles of more than 80% of an original specific energyof from 600 Wh·kg⁻¹ to 1000 Wh·kg⁻¹.

Aspect 40 is the electrode active material of any previous or subsequentaspect, exhibiting or characterized by a specific energy after 1000charge-discharge cycles of more than 85% of an original specific energyof from 600 Wh·kg⁻¹ to 1000 Wh·kg⁻¹.

Aspect 41 is the electrode active material of any previous or subsequentaspect, exhibiting or characterized by a specific energy after 500charge-discharge cycles of more than 90% of an original specific energyof from 600 Wh·kg⁻¹ to 1000 Wh·kg⁻¹.

Aspect 42 is the electrode active material of any previous or subsequentaspect, exhibiting or characterized by a specific energy after 100charge-discharge cycles of more than 95% of an original specific energyof from 600 Wh·kg⁻¹ to 1000 Wh·kg⁻¹.

Aspect 43 is the electrode active material of any previous or subsequentaspect, wherein only a portion comprises or is characterized by arhombohedral crystal structure or a rhombohedral R3m crystal structure.

Aspect 44 is the electrode active material of any previous or subsequentaspect, wherein 99 volume percent or less of the electrode activematerial comprises or is characterized by a rhombohedral crystalstructure or a rhombohedral R3m crystal structure.

Aspect 45 is the electrode active material of any previous or subsequentaspect, having or characterized by a surface region and a bulk region,wherein the surface region corresponds to a first portion of the activematerial or particles thereof within 20% of a cross-sectional dimensionfrom a surface of the active material or particles thereof, and whereinthe bulk region corresponds to a second portion of the active materialor particles thereof deeper than the surface region.

Aspect 46 is the electrode active material of any previous or subsequentaspect, wherein the bulk region is free or substantially free of or doesnot exhibit a spinel, P4₃32 or Fd3m crystal structure, a lithium-excessor C2/m crystal structure, or a rock salt or Fm3m crystal structure.

Aspect 47 is the electrode active material of any previous or subsequentaspect, wherein at least a portion of the surface region comprises or ischaracterized by a spinel, P4₃32 or Fd3m crystal structure, alithium-excess or C2/m crystal structure, or a rock salt or Fm3m crystalstructure.

Aspect 48 is the electrode active material of any previous or subsequentaspect, wherein the bulk region is free or substantially free of or doesnot exhibit LiFePO₄ (Pmnb/Pnma) or another polyanionic structure.

Aspect 49 is the electrode active material of any previous or subsequentaspect, wherein at least a portion of the surface region comprises or ischaracterized by LiFePO₄ (Pmnb/Pnma) or another polyanionic structure.

Aspect 50 is the electrode active material of any previous or subsequentaspect, comprising particles of Li_(a)N_(1-b-c)Co_(b)M_(c)O_(d) havingcross-sectional dimensions of from 500 nm to 30 μm.

Aspect 51 is the electrode active material of any previous or subsequentaspect, comprising a plurality of secondary particles.

Aspect 52 is the electrode active material of any previous or subsequentaspect, wherein the plurality of secondary particles havecross-sectional dimensions of from 500 nm to 30 μm.

Aspect 53 is the electrode active material of any previous or subsequentaspect, wherein the plurality of secondary particles havecross-sectional dimensions of from 500 nm to 2.5 μm.

Aspect 54 is the electrode active material of any previous or subsequentaspect, wherein the plurality of secondary particles havecross-sectional dimensions of from 2.5 μm to 7.5 μm.

Aspect 55 is the electrode active material of any previous or subsequentaspect, wherein the plurality of secondary particles havecross-sectional dimensions of from 7.5 μm to 15 μm.

Aspect 56 is the electrode active material of any previous or subsequentaspect, wherein the plurality of secondary particles havecross-sectional dimensions of from 15 μm to 30 μm.

Aspect 57 is the electrode active material of any previous or subsequentaspect, wherein the plurality of secondary particles are substantiallymonodisperse.

Aspect 58 is the electrode active material of any previous or subsequentaspect, wherein the plurality of secondary particles are polydisperseand comprise a first portion having a first cross-sectional dimensiondistribution and a second portion having a second cross-sectionaldimension distribution that is at least a factor of 10 larger than thefirst cross-sectional dimension distribution.

Aspect 59 is the electrode active material of any previous or subsequentaspect, wherein the plurality of secondary particles are substantiallyspherical in shape.

Aspect 60 is the electrode active material of any previous or subsequentaspect, wherein at least some of the secondary particles each comprise aplurality of primary particles.

Aspect 61 is the electrode active material of any previous or subsequentaspect, wherein the plurality of primary particles have cross-sectionaldimensions of from 10 nm to 10 μm.

Aspect 62 is the electrode active material of any previous or subsequentaspect, wherein the plurality of primary particles have cross-sectionaldimensions of from 10 nm to 100 nm.

Aspect 63 is the electrode active material of any previous or subsequentaspect, wherein the plurality of primary particles have cross-sectionaldimensions of from 100 nm to 1000 nm.

Aspect 64 is the electrode active material of any previous or subsequentaspect, wherein the plurality of primary particles have cross-sectionaldimensions of from 1 μm to 10 μm.

Aspect 65 is the electrode active material of any previous or subsequentaspect, wherein the plurality of primary particles are substantiallymonodisperse.

Aspect 66 is the electrode active material of any previous or subsequentaspect, wherein at least some of the secondary particles eachindependently consist of one primary particle.

Aspect 67 is the electrode active material of any previous or subsequentaspect, exhibiting or characterized by a specific energy for a 1 Cdischarge rate between 5 V and 3 V vs. Li⁺/Li of from 80% to 100% of aspecific energy for a C/10 discharge rate between 5 V and 3 V vs. Li⁺/Liat 25° C.

Aspect 68 is the electrode active material of any previous or subsequentaspect, exhibiting or characterized by a specific energy for a 1 Cdischarge rate between 5 V and 3 V vs. Li⁺/Li of from 85% to 100% of thespecific energy for a C/10 discharge rate between 5 V and 3 V vs. Li⁺/Liat 25° C.

Aspect 69 is the electrode active material of any previous or subsequentaspect, exhibiting or characterized by a specific energy for a 1 Cdischarge rate between 5 V and 3 V vs. Li⁺/Li of from 90% to 100% of thespecific energy for a C/10 discharge rate between 5 V and 3 V vs. Li⁺/Liat 25° C.

Aspect 70 is the electrode active material of any previous or subsequentaspect, exhibiting or characterized by a specific energy for a 1 Cdischarge rate between 5 V and 3 V vs. Li⁺/Li of from 750 Wh·kg⁻¹ to1000 Wh·kg⁻¹ at 25° C.

Aspect 71 is an electrode comprising the electrode active material ofany previous aspect.

Aspect 72 is the electrode of any previous aspect, further comprising acurrent collector.

Aspect 73 is an electrochemical cell, comprising: a cathode comprisingthe electrode of any previous aspect; an anode; and an electrolytebetween the cathode and the anode.

Aspect 74 is the electrochemical cell of any previous or subsequentaspect, wherein the anode comprises graphite, carbon, silicon, lithiumtitanate (Li₄Ti₅O₁₂), tin, antimony, zinc, phosphorous, lithium, or acombination thereof.

Aspect 75 is the electrochemical cell of any previous or subsequentaspect, wherein the cathode or the anode or both independently compriseone or more of an active material, a current collector, a solidelectrolyte, a binder, or a conductive additive.

Aspect 76 is the electrochemical cell of any previous or subsequentaspect, wherein the electrolyte is a liquid electrolyte.

Aspect 77 is the electrochemical cell of any previous or subsequentaspect, wherein the electrolyte is a semi-solid electrolyte.

Aspect 78 is the electrochemical cell of any previous or subsequentaspect, wherein the electrolyte is a solid electrolyte.

Aspect 79 is the electrochemical cell of any previous or subsequentaspect, wherein the electrolyte is a non-aqueous electrolyte.

STATEMENTS REGARDING INCORPORATION BY REFERENCE AND VARIATIONS

All references throughout this application, for example patent documentsincluding issued or granted patents or equivalents; patent applicationpublications; and non-patent literature documents or other sourcematerial; are hereby incorporated by reference herein in theirentireties, as though individually incorporated by reference.

All patents and publications mentioned in the specification areindicative of the levels of skill of those skilled in the art to whichthe invention pertains. References cited herein are incorporated byreference herein in their entirety to indicate the state of the art, insome cases as of their filing date, and it is intended that thisinformation can be employed herein, if needed, to exclude (for example,to disclaim) specific embodiments that are in the prior art.

When a group of substituents is disclosed herein, it is understood thatall individual members of those groups and all subgroups and classesthat can be formed using the substituents are disclosed separately. Whena Markush group or other grouping is used herein, all individual membersof the group and all combinations and subcombinations possible of thegroup are intended to be individually included in the disclosure. Asused herein, “and/or” means that one, all, or any combination of itemsin a list separated by “and/or” are included in the list; for example“1, 2 and/or 3” is equivalent to “‘1’ or ‘2’ or ‘3’ or ‘1 and 2’ or ‘1and 3’ or ‘2 and 3’ or ‘1, 2 and 3’”.

Every formulation or combination of components described or exemplifiedcan be used to practice the invention, unless otherwise stated. Specificnames of materials are intended to be exemplary, as it is known that oneof ordinary skill in the art can name the same material differently. Itwill be appreciated that methods, device elements, starting materials,and synthetic methods other than those specifically exemplified can beemployed in the practice of the invention without resort to undueexperimentation. All art-known functional equivalents, of any suchmethods, device elements, starting materials, and synthetic methods areintended to be included in this invention. Whenever a range is given inthe specification, for example, a temperature range, a time range, or acomposition range, all intermediate ranges and subranges, as well as allindividual values included in the ranges given are intended to beincluded in the disclosure.

As used herein, “comprising” is synonymous with “including,”“containing,” or “characterized by,” and is inclusive or open-ended anddoes not exclude additional, unrecited elements or method steps. As usedherein, “consisting of” excludes any element, step, or ingredient notspecified in the claim element. As used herein, “consisting essentiallyof” does not exclude materials or steps that do not materially affectthe basic and novel characteristics of the claim. Any recitation hereinof the term “comprising”, particularly in a description of components ofa composition or in a description of elements of a device, is understoodto encompass those compositions and methods consisting essentially ofand consisting of the recited components or elements. The inventionillustratively described herein suitably may be practiced in the absenceof any element or elements, limitation or limitations which is notspecifically disclosed herein.

The terms and expressions which have been employed are used as terms ofdescription and not of limitation, and there is no intention in the useof such terms and expressions of excluding any equivalents of thefeatures shown and described or portions thereof, but it is recognizedthat various modifications are possible within the scope of theinvention claimed. Thus, it should be understood that although thepresent invention has been specifically disclosed by preferredembodiments and optional features, modification and variation of theconcepts herein disclosed may be resorted to by those skilled in theart, and that such modifications and variations are considered to bewithin the scope of this invention as defined by the appended claims.

What is claimed is:
 1. An electrode active material comprising:Li_(a)Ni_(1-b-c)Co_(b)M_(c)O_(d), wherein: a is from 0.9 to 1.1, b isfrom 0 to 0.05, c is from 0 to 0.67, d is from 1.9 to 2.1, and M is Mn,Al, Mg, Fe, Cr, B, Ti, Zr, Ga, Zn, V, Cu, Yb, Li, Na, K, F, Ba, Ca, Lu,Y, Nb, Mo, Ru, Rh, Ta, Pr, W, Ir, In, Tl, Sn, Sr, S, P, Cl, Ge, Sb, Er,Te, La, Ce, Nd, Dy, Eu, Sc, Se, Si, Tc, Pd, Pm, Sm, Gd, Tb, Ho, Tm, orany combination of these, the Li_(a)Ni_(1-b-c)Co_(b)M_(c)O_(d)comprising a plurality of secondary particles, the secondary particlescomprising a plurality of primary particles, wherein: the plurality ofsecondary particles are substantially spherical in shape, and theplurality of secondary particles have an average secondary particlesize, wherein at least about 80% of the secondary particles have asecondary particle size that is within a specified secondary particlesize range of from about 50% to about 200% of the average secondaryparticle size.
 2. The electrode active material of claim 1, wherein b isfrom 0 to 0.03.
 3. The electrode active material of claim 1, wherein cis from 0.05 to 0.40.
 4. The electrode active material of claim 1,wherein 1-b-c is from 0.60 to 0.95.
 5. The electrode active material ofclaim 1, wherein M comprises one or more of Mn, Al, or Mg.
 6. Theelectrode active material of claim 1, wherein the plurality of primaryparticles have cross-sectional dimensions of from 10 nm to 10 μm.
 7. Theelectrode active material of claim 1, exhibiting or characterized by anoriginal specific energy for a first discharge of from 600 Wh·kg⁻¹ to1000 Wh·kg⁻¹ and a specific energy for another discharge after about 500charge-discharge cycles of from 480 Wh·kg⁻¹ to 1000 Wh·kg⁻¹.
 8. Anelectrode comprising the electrode active material of claim
 1. 9. Anelectrochemical cell comprising: a cathode, the cathode comprising theelectrode of claim 8; an anode; and an electrolyte between the cathodeand the anode.
 10. The electrochemical cell of claim 9, wherein theanode comprises graphite, carbon, silicon, lithium titanate (Li₄Ti₅O₁₂),tin, antimony, zinc, phosphorous, lithium, or a combination thereof, andwherein the electrolyte is a liquid electrolyte, a semi-solidelectrolyte, or a solid electrolyte.
 11. An electrode active materialcomprising: Li_(a)Ni_(1-b-c)Co_(b)M_(c)O_(d), wherein: a is from 0.9 to1.1, b is from 0 to 0.05, c is from 0 to 0.67, d is from 1.9 to 2.1, andM is Mn, Al, Mg, Fe, Cr, B, Ti, Zr, Ga, Zn, V, Cu, Yb, Li, Na, K, F, Ba,Ca, Lu, Y, Nb, Mo, Ru, Rh, Ta, Pr, W, Ir, In, Tl, Sn, Sr, S, P, Cl, Ge,Sb, Er, Te, La, Ce, Nd, Dy, Eu, Sc, Se, Si, Tc, Pd, Pm, Sm, Gd, Tb, Ho,Tm, or any combination of these, the Li_(a)Ni_(1-b-c)Co_(b)M_(c)O_(d)comprising a plurality of secondary particles, the secondary particlescomprising a plurality of primary particles, wherein the plurality ofprimary particles have cross-sectional dimensions of from about 50 nm to1 μm.
 12. The electrode active material of claim 11, wherein b is from 0to 0.03.
 13. The electrode active material of claim 11, wherein c isfrom 0.04 to 0.30
 14. The electrode active material of claim 11, wherein1-b-c is from 0.60 to 0.95.
 15. The electrode active material of claim11, wherein M comprises one or more of Mn, Al, or Mg.
 16. The electrodeactive material of claim 11, wherein the plurality of secondaryparticles have cross-sectional dimensions of from 500 nm to 30 μm. 17.The electrode active material of claim 11, exhibiting or characterizedby an original specific energy for a first discharge of from 600 Wh·kg⁻¹to 1000 Wh·kg⁻¹ and a specific energy for another discharge after about500 charge-discharge cycles of from 480 Wh·kg⁻¹ to 1000 Wh·kg⁻¹.
 18. Anelectrode comprising the electrode active material of claim
 11. 19. Anelectrochemical cell comprising: a cathode, the cathode comprising theelectrode of claim 18; an anode; and an electrolyte between the cathodeand the anode.
 20. The electrochemical cell of claim 19, wherein theanode comprises graphite, carbon, silicon, lithium titanate (Li₄Ti₅O₁₂),tin, antimony, zinc, phosphorous, lithium, or a combination thereof, andwherein the electrolyte is a liquid electrolyte, a semi-solidelectrolyte, or a solid electrolyte.